Updated the expiration handler to be abstract and to work on databases
Merge branch 'abstract-session-handler-expiration' of https://github.com/bashaus/laravel-framework into abstract-session-handler-expiration

Conflicts:
	src/Illuminate/Session/DatabaseSessionHandler.php
	src/Illuminate/Session/ExpirationAwareInterface.php
	src/Illuminate/Session/ExpirationAwareSessionHandler.php
	tests/Session/CookieSessionHandlerTest.php
	tests/Session/ExpirationAwareSessionHandlerTest.php