Add subclassing hook to ProviderConfigurationSupport to allow the constr...

The getApi() method of ApiHelper returns a non user-specific API binding if a user-specific connection is not available (eg FacebookApiHelper returns default FacebookTemplate).

For some providers, the construction of this non user-specific binding will require constructor args - for example SoundCloudTemplate and LastFmTemplate both require apiKey for all operations,  TwitterTemplate will require appKey,appSecret and client authentication scope to obtain a client authenticated access token.

Add a subclassing hook to ProviderConfigurationSupport  ( getApiHelperBeanDefinitionBuilder() method ) to allow provider implementations to configure the ApiHelper bean with additional parameters.