moved getConfiguration from XMPPConnection to AbstractXMPPConnection
restore  the XMPPConnection parameter in the Roster and added two new methods to the interface.
moved getConfiguration from XMPPConnection to AbstractXMPPConnection
restore  the XMPPConnection parameter in the Roster and added two new methods to the interface.
rebased commits for pull request
Merge branch 'get_configuration_visibility' of github.com:BugsBunnyBR/Smack into get_configuration_visibility

Conflicts:
	smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java