Introduce guzzle.plugins parameter
Merge remote-tracking branch 'upstream/master' into plugin-param

* upstream/master:
  Fixing README. Closes #14. Removed unused parameter from provider.
  Add branch-alias to composer.json
  Remove class_path option
  Remove version field from composer.json

Conflicts:
	GuzzleServiceProvider.php
Fix conflict
Merge pull request #12 from igorw/plugin-param

Introduce guzzle.plugins parameter