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/github.com/ugorji/go/codec/helper.go

@@ -391,6 +391,10 @@ var immutableKindsSet = [32]bool{
 // Any type which implements Selfer will be able to encode or decode itself.
 // Consequently, during (en|de)code, this takes precedence over
 // (text|binary)(M|Unm)arshal or extension support.
+//
+// Note: *the first set of bytes of any value MUST NOT represent nil in the format*.
+// This is because, during each decode, we first check the the next set of bytes
+// represent nil, and if so, we just set the value to nil.
 type Selfer interface {
 	CodecEncodeSelf(*Encoder)
 	CodecDecodeSelf(*Decoder)
@@ -1543,6 +1547,8 @@ func isEmptyStruct(v reflect.Value, tinfos *TypeInfos, deref, checkStruct bool)
 // }
 
 func panicToErr(h errstrDecorator, err *error) {
+	// Note: This method MUST be called directly from defer i.e. defer panicToErr ...
+	// else it seems the recover is not fully handled
 	if recoverPanicToErr {
 		if x := recover(); x != nil {
 			// fmt.Printf("panic'ing with: %v\n", x)
@@ -1552,15 +1558,6 @@ func panicToErr(h errstrDecorator, err *error) {
 	}
 }
 
-func panicToErrs2(h errstrDecorator, err1, err2 *error) {
-	if recoverPanicToErr {
-		if x := recover(); x != nil {
-			panicValToErr(h, x, err1)
-			panicValToErr(h, x, err2)
-		}
-	}
-}
-
 func panicValToErr(h errstrDecorator, v interface{}, err *error) {
 	switch xerr := v.(type) {
 	case nil: