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/google.golang.org/api/tpu/v1alpha1/tpu-api.json

@@ -9,7 +9,7 @@
     }
   },
   "basePath": "",
-  "baseUrl": "https://content-tpu.googleapis.com/",
+  "baseUrl": "https://tpu.googleapis.com/",
   "batchPath": "batch",
   "canonicalName": "TPU",
   "description": "TPU API provides customers with access to Google TPU technology.",
@@ -120,7 +120,7 @@
         "locations": {
           "methods": {
             "get": {
-              "description": "Get information about a location.",
+              "description": "Gets information about a location.",
               "flatPath": "v1alpha1/projects/{projectsId}/locations/{locationsId}",
               "httpMethod": "GET",
               "id": "tpu.projects.locations.get",
@@ -697,8 +697,8 @@
       }
     }
   },
-  "revision": "20180303",
-  "rootUrl": "https://content-tpu.googleapis.com/",
+  "revision": "20180411",
+  "rootUrl": "https://tpu.googleapis.com/",
   "schemas": {
     "AcceleratorType": {
       "description": "A accelerator type that a Node can be configured with.",
@@ -946,7 +946,9 @@
             "REIMAGING",
             "DELETING",
             "REPAIRING",
-            "STOPPED"
+            "STOPPED",
+            "STOPPING",
+            "STARTING"
           ],
           "enumDescriptions": [
             "TPU node state is not known/set.",
@@ -956,7 +958,9 @@
             "TPU node is undergoing reimaging.",
             "TPU node is being deleted.",
             "TPU node is being repaired and may be unusable. Details can be\nfound in the `help_description` field.",
-            "7 - Reserved. Was SUSPENDED.\nTPU node is stopped."
+            "7 - Reserved. Was SUSPENDED.\nTPU node is stopped.",
+            "TPU node is currently stopping.",
+            "TPU node is currently starting."
           ],
           "type": "string"
         },

vendor/google.golang.org/api/tpu/v1alpha1/tpu-gen.go

@@ -43,7 +43,7 @@ var _ = ctxhttp.Do
 const apiId = "tpu:v1alpha1"
 const apiName = "tpu"
 const apiVersion = "v1alpha1"
-const basePath = "https://content-tpu.googleapis.com/"
+const basePath = "https://tpu.googleapis.com/"
 
 // OAuth2 scopes used by this API.
 const (
@@ -571,6 +571,8 @@ type Node struct {
 	// found in the `help_description` field.
 	//   "STOPPED" - 7 - Reserved. Was SUSPENDED.
 	// TPU node is stopped.
+	//   "STOPPING" - TPU node is currently stopping.
+	//   "STARTING" - TPU node is currently starting.
 	State string `json:"state,omitempty"`
 
 	// TensorflowVersion: The version of Tensorflow running in the
@@ -943,7 +945,7 @@ type ProjectsLocationsGetCall struct {
 	header_      http.Header
 }
 
-// Get: Get information about a location.
+// Get: Gets information about a location.
 func (r *ProjectsLocationsService) Get(name string) *ProjectsLocationsGetCall {
 	c := &ProjectsLocationsGetCall{s: r.s, urlParams_: make(gensupport.URLParams)}
 	c.name = name
@@ -1044,7 +1046,7 @@ func (c *ProjectsLocationsGetCall) Do(opts ...googleapi.CallOption) (*Location,
 	}
 	return ret, nil
 	// {
-	//   "description": "Get information about a location.",
+	//   "description": "Gets information about a location.",
 	//   "flatPath": "v1alpha1/projects/{projectsId}/locations/{locationsId}",
 	//   "httpMethod": "GET",
 	//   "id": "tpu.projects.locations.get",