Throw InvalidCredentialsException with GoogleMBP

* When an invalid clientID / privateKey
  combination is used with the
  GoogleMapsBusinessProvider, throw an
  InvalidCredentialsException instead of a
  NoResultException.

* Test that the exception is thrown with the
  testGetGeocodedDataWithInvalidClientIdAndKey(),
  and
  testGetGeocodedDataWithINvalidClientIdAndKeyNoSsl()
  methods.

* Add two tests for the GoogleMapsProvider to
  test that expected results are returned when using
  a valid API Key (commented example added to
  phpunit.xml.dist and README.md) and that an
  InvalidCredentialsException is thrown when an
  incorrect API Key is used.
Merge pull request #315 from Decave/314-throw_invalid_credentials_exception_with_bad_google_maps_key

Throw InvalidCredentialsException with GoogleMBP