OPENDJ-808 Implement a simple commons REST based HTTP connection handler

TLSCapableConnection.java:
Renamed isTLSAvailable() to isStartTLSAvailable() to better explicit the purpose of this method.
 
StartTLSExtendedOperation.java:
Consequence of the change to TLSCapableConnection.

LDAPClientConnection.java:
Consequence of the change to TLSCapableConnection.
Used StaticUtils.close() methods.
Removed one useless parameter from ConnectionFinalizerJob constructor.

StaticUtils.java:
Added close(Selector...).