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/replicapool/v1beta1/replicapool-api.json

@@ -29,7 +29,7 @@
   "description": "The Replica Pool API allows users to declaratively provision and manage groups of Google Compute Engine instances based on a common template.",
   "discoveryVersion": "v1",
   "documentationLink": "https://developers.google.com/compute/docs/replica-pool/",
-  "etag": "\"-iA1DTNe4s-I6JZXPt1t1Ypy8IU/jlteK0NbZ8atlXF9lM-OU-ZamcA\"",
+  "etag": "\"Zkyw9ACJZUvcYmlFaKGChzhmtnE/vkT-xkmU9XwOepJLLEd3mTrcuvQ\"",
   "icons": {
     "x16": "https://www.gstatic.com/images/branding/product/1x/googleg_16dp.png",
     "x32": "https://www.gstatic.com/images/branding/product/1x/googleg_32dp.png"
@@ -77,12 +77,12 @@
       "type": "boolean"
     },
     "quotaUser": {
-      "description": "Available to use for quota purposes for server-side applications. Can be any arbitrary string assigned to a user, but should not exceed 40 characters. Overrides userIp if both are provided.",
+      "description": "An opaque string that represents a user for quota purposes. Must not exceed 40 characters.",
       "location": "query",
       "type": "string"
     },
     "userIp": {
-      "description": "IP address of the site where the request originates. Use this if you want to enforce per-user limits.",
+      "description": "Deprecated. Please use quotaUser instead.",
       "location": "query",
       "type": "string"
     }

vendor/google.golang.org/api/replicapool/v1beta2/replicapool-api.json

@@ -23,7 +23,7 @@
   "description": "[Deprecated. Please use Instance Group Manager in Compute API] Provides groups of homogenous Compute Engine instances.",
   "discoveryVersion": "v1",
   "documentationLink": "https://developers.google.com/compute/docs/instance-groups/manager/v1beta2",
-  "etag": "\"-iA1DTNe4s-I6JZXPt1t1Ypy8IU/TeJ87k5AaNhxSfkpXHKHkISW9Dw\"",
+  "etag": "\"Zkyw9ACJZUvcYmlFaKGChzhmtnE/iHkuiJpugjT1_Yp5ikwD4uaLgZ4\"",
   "icons": {
     "x16": "https://www.gstatic.com/images/branding/product/1x/googleg_16dp.png",
     "x32": "https://www.gstatic.com/images/branding/product/1x/googleg_32dp.png"
@@ -71,12 +71,12 @@
       "type": "boolean"
     },
     "quotaUser": {
-      "description": "Available to use for quota purposes for server-side applications. Can be any arbitrary string assigned to a user, but should not exceed 40 characters. Overrides userIp if both are provided.",
+      "description": "An opaque string that represents a user for quota purposes. Must not exceed 40 characters.",
       "location": "query",
       "type": "string"
     },
     "userIp": {
-      "description": "IP address of the site where the request originates. Use this if you want to enforce per-user limits.",
+      "description": "Deprecated. Please use quotaUser instead.",
       "location": "query",
       "type": "string"
     }