Automatically add client=gme-xxx when signing
Google Maps for Business geocoding test

- Recategorise live tests:
  - Now in the "External integrations" category
  - They must be run explicitly
Added request signing example and removed "coming soon".
Merge branch 'request-signing' of https://github.com/richardthombs/gmaps-api-net into richardthombs-request-signing

Conflicts:
	README.md
	src/Google.Maps/GoogleSigned.cs
removed reference to file not checked in that was causing build problems