Fix for bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=455279

Change-Id: I02f08ab44534625a19396da04d5693bd3f0259dd
Refactoring of RestClientContainer and RestClientService by adding
AbstractRestClientContainer and AbstractRestClientService.

Change-Id: I05f6422dd75d3ec2ac58a49bb394fd7b4ae030b3