Update SDK to latest stone spec (#57)

* full patch with tests:

* simplified

* fix fmt_type to get things compiling

* drop missing import

* simpler union decoding

* update sdk version

* update api spec to latest version (#2)

* force SDK version update

* fix basd commit in types

Author: aaronstaley

dropbox/auth/types.go

@@ -79,6 +79,9 @@ func (u *AccessError) UnmarshalJSON(body []byte) error {
 // AuthError : Errors occurred during authentication.
 type AuthError struct {
 	dropbox.Tagged
+	// MissingScope : The access token does not have the required scope to
+	// access the route.
+	MissingScope *TokenScopeError `json:"missing_scope,omitempty"`
 }
 
 // Valid tag values for AuthError
@@ -88,9 +91,32 @@ const (
 	AuthErrorInvalidSelectAdmin = "invalid_select_admin"
 	AuthErrorUserSuspended      = "user_suspended"
 	AuthErrorExpiredAccessToken = "expired_access_token"
+	AuthErrorMissingScope       = "missing_scope"
 	AuthErrorOther              = "other"
 )
 
+// UnmarshalJSON deserializes into a AuthError instance
+func (u *AuthError) UnmarshalJSON(body []byte) error {
+	type wrap struct {
+		dropbox.Tagged
+	}
+	var w wrap
+	var err error
+	if err = json.Unmarshal(body, &w); err != nil {
+		return err
+	}
+	u.Tag = w.Tag
+	switch u.Tag {
+	case "missing_scope":
+		err = json.Unmarshal(body, &u.MissingScope)
+
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // InvalidAccountTypeError : has no documentation (yet)
 type InvalidAccountTypeError struct {
 	dropbox.Tagged
@@ -186,3 +212,16 @@ func NewTokenFromOAuth1Result(Oauth2Token string) *TokenFromOAuth1Result {
 	s.Oauth2Token = Oauth2Token
 	return s
 }
+
+// TokenScopeError : has no documentation (yet)
+type TokenScopeError struct {
+	// RequiredScope : The required scope to access the route.
+	RequiredScope string `json:"required_scope"`
+}
+
+// NewTokenScopeError returns a new TokenScopeError instance
+func NewTokenScopeError(RequiredScope string) *TokenScopeError {
+	s := new(TokenScopeError)
+	s.RequiredScope = RequiredScope
+	return s
+}