Source google cloud sdk path and completion files

We are now installing google-cloud-sdk and Deis with Homebrew using
brew bundle.

dotfiles/profile.d/google

@@ -0,0 +1,18 @@
+#!/bin/bash -e
+
+source_google_cloud_sdk_file() {
+  local filename=$1
+  local path="/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk"
+  if [ -f "$path/$filename" ]; then
+    # shellcheck disable=SC1090
+    source "$path/$filename"
+  fi
+}
+
+# Updates PATH for the Google Cloud SDK.
+source_google_cloud_sdk_file "path.bash.inc"
+
+# Enables shell command completion for gcloud.
+source_google_cloud_sdk_file "completion.bash.inc"
+
+unset -f source_google_cloud_sdk_file