update use statement to Guzzle 3.* structure
update Configuration to get it working with single string represent a service description file-path. Should also work with services configured in the config file format.
update to get rid of broken service due to PluginCollectionPlugin class being removed from Guzzle library.
Removed type from argument to allow either string or array to be passed to the factory method.
formatting
add global configuration parameter allow factory method definition to match method signature
update docs