Add InvalidProviderException.
Require PHP 5.4 or higher.
Simplify abstract connector and get rid of tight coupling.
Add ConnectorFactory.
Clean up unused code.
More code reorganization for AbstractConnector and ConnectorFactory.
Simplify ConnectorFactory::createConnector by setting the configuration in the constructor.
This way a single factory instance can also be reused for creating multiple connectors (like a "factory" should).
Make providing a flat array a responsibility of the ConnectorFactory,
Initial test for ConnectorFactory. Remove test for Socializr.
Remove unused code.
Fix static property access.
Add test for exception thrown when invalid connector is requested.
Allow separate service configuration for connectors.

For example, a FacebookPage connector cannot instantiate a
FacebookPage service from PHPoAuthLib because it doesn't exist,
so it should use the Facebook service instead. For that to happen,
the FacebookPage key in the configuration array (which is itself another
array) should have a 'service' key, defining which PHPoAuthLib service
to use.
Throw exception if ConnectorFactory config array is empty
Add Scrutinizer badges.
Change the build status from Scrutinizer to Travis.
Convert readme file to Markdown.
Document the ConnectorFactory methods.
Remove no longer needed Socializr class.
Fix parameter type in docs.