functions: hot containers (#332)

* functions: modify datastore to accomodate hot containers support

* functions: protocol between functions and hot containers

* functions: add hot containers clockwork

* fn: add hot containers support

api/runner/task/task.go

@@ -0,0 +1,40 @@
+package task
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"github.com/iron-io/runner/drivers"
+)
+
+type Config struct {
+	ID             string
+	Path           string
+	Image          string
+	Timeout        time.Duration
+	AppName        string
+	Memory         uint64
+	Env            map[string]string
+	Format         string
+	MaxConcurrency int
+
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+}
+
+// Request stores the task to be executed by the common concurrency stream,
+// whatever type the ask actually is, either sync or async. It holds in itself
+// the channel to return its response to its caller.
+type Request struct {
+	Ctx      context.Context
+	Config   *Config
+	Response chan Response
+}
+
+// Response holds the response metainformation of a Request
+type Response struct {
+	Result drivers.RunResult
+	Err    error
+}