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/Azure/azure-sdk-for-go/doc.go

@@ -0,0 +1,26 @@
+/*
+Package sdk provides Go packages for managing and using Azure services.
+
+GitHub repo: https://github.com/Azure/azure-sdk-for-go
+
+Official documentation: https://docs.microsoft.com/go/azure
+
+API reference: https://godoc.org/github.com/Azure/azure-sdk-for-go
+
+Samples: https://github.com/Azure-Samples/azure-sdk-for-go-samples
+*/
+package sdk
+
+// Copyright (c) Microsoft and contributors.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//
+// See the License for the specific language governing permissions and
+// limitations under the License.