Bye bye openapi (#1081)

* add DateTime sans mgo

* change all uses of strfmt.DateTime to common.DateTime, remove test strfmt usage

* remove api tests, system-test dep on api test

multiple reasons to remove the api tests:

* awkward dependency with fn_go meant generating bindings on a branched fn to
vendor those to test new stuff. this is at a minimum not at all intuitive,
worth it, nor a fun way to spend the finite amount of time we have to live.
* api tests only tested a subset of functionality that the server/ api tests
already test, and we risk having tests where one tests some thing and the
other doesn't. let's not. we have too many test suites as it is, and these
pretty much only test that we updated the fn_go bindings, which is actually a
hassle as noted above and the cli will pretty quickly figure out anyway.
* fn_go relies on openapi, which relies on mgo, which is deprecated and we'd
like to remove as a dependency. openapi is a _huge_ dep built in a NIH
fashion, that cannot simply remove the mgo dep as users may be using it.
we've now stolen their date time and otherwise killed usage of it in fn core,
for fn_go it still exists but that's less of a problem.

* update deps

removals:

* easyjson
* mgo
* go-openapi
* mapstructure
* fn_go
* purell
* go-validator

also, had to lock docker. we shouldn't use docker on master anyway, they
strongly advise against that. had no luck with latest version rev, so i locked
it to what we were using before. until next time.

the rest is just playing dep roulette, those end up removing a ton tho

* fix exec test to work

* account for john le cache

vendor/golang.org/x/net/webdav/prop.go

@@ -7,6 +7,7 @@ package webdav
 import (
 	"bytes"
 	"encoding/xml"
+	"errors"
 	"fmt"
 	"io"
 	"mime"
@@ -376,10 +377,37 @@ func findContentLength(ctx context.Context, fs FileSystem, ls LockSystem, name s
 }
 
 func findLastModified(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
-	return fi.ModTime().Format(http.TimeFormat), nil
+	return fi.ModTime().UTC().Format(http.TimeFormat), nil
+}
+
+// ErrNotImplemented should be returned by optional interfaces if they
+// want the original implementation to be used.
+var ErrNotImplemented = errors.New("not implemented")
+
+// ContentTyper is an optional interface for the os.FileInfo
+// objects returned by the FileSystem.
+//
+// If this interface is defined then it will be used to read the
+// content type from the object.
+//
+// If this interface is not defined the file will be opened and the
+// content type will be guessed from the initial contents of the file.
+type ContentTyper interface {
+	// ContentType returns the content type for the file.
+	//
+	// If this returns error ErrNotImplemented then the error will
+	// be ignored and the base implementation will be used
+	// instead.
+	ContentType(ctx context.Context) (string, error)
 }
 
 func findContentType(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
+	if do, ok := fi.(ContentTyper); ok {
+		ctype, err := do.ContentType(ctx)
+		if err != ErrNotImplemented {
+			return ctype, err
+		}
+	}
 	f, err := fs.OpenFile(ctx, name, os.O_RDONLY, 0)
 	if err != nil {
 		return "", err
@@ -402,7 +430,31 @@ func findContentType(ctx context.Context, fs FileSystem, ls LockSystem, name str
 	return ctype, err
 }
 
+// ETager is an optional interface for the os.FileInfo objects
+// returned by the FileSystem.
+//
+// If this interface is defined then it will be used to read the ETag
+// for the object.
+//
+// If this interface is not defined an ETag will be computed using the
+// ModTime() and the Size() methods of the os.FileInfo object.
+type ETager interface {
+	// ETag returns an ETag for the file.  This should be of the
+	// form "value" or W/"value"
+	//
+	// If this returns error ErrNotImplemented then the error will
+	// be ignored and the base implementation will be used
+	// instead.
+	ETag(ctx context.Context) (string, error)
+}
+
 func findETag(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
+	if do, ok := fi.(ETager); ok {
+		etag, err := do.ETag(ctx)
+		if err != ErrNotImplemented {
+			return etag, err
+		}
+	}
 	// The Apache http 2.4 web server by default concatenates the
 	// modification time and size of a file. We replicate the heuristic
 	// with nanosecond granularity.