vendor: update all dependencies

* Update all dependencies
  * Remove all `[[constraint]]` from Gopkg.toml
  * Add in the minimum number of `[[override]]` to build
  * Remove go get of github.com/inconshreveable/mousetrap as it is vendored
  * Update docs with new policy on constraints

vendor/github.com/aws/aws-sdk-go/private/model/api/shape.go

@@ -55,9 +55,9 @@ type Shape struct {
 	ShapeName        string
 	Documentation    string
 	MemberRefs       map[string]*ShapeRef `json:"members"`
-	MemberRef        ShapeRef             `json:"member"`
-	KeyRef           ShapeRef             `json:"key"`
-	ValueRef         ShapeRef             `json:"value"`
+	MemberRef        ShapeRef             `json:"member"` // List ref
+	KeyRef           ShapeRef             `json:"key"`    // map key ref
+	ValueRef         ShapeRef             `json:"value"`  // map value ref
 	Required         []string
 	Payload          string
 	Type             string
@@ -73,6 +73,8 @@ type Shape struct {
 	Min              float64 // optional Minimum length (string, list) or value (number)
 	Max              float64 // optional Maximum length (string, list) or value (number)
 
+	IsEventStream bool `json:"eventstream"`
+
 	refs       []*ShapeRef // References to this shape
 	resolvePkg string      // use this package in the goType() if present