Implementing the User communication with the server

modified:   src/br/ufrn/dimap/pubshare/activity/RegisterActivity.java
	modified:   src/br/ufrn/dimap/pubshare/adapters/FriendsListAdapter.java
        new file:   src/br/ufrn/dimap/pubshare/domain/Friend.java
	new file:   src/br/ufrn/dimap/pubshare/domain/Tag.java
	modified:   src/br/ufrn/dimap/pubshare/domain/User.java
	modified:   src/br/ufrn/dimap/pubshare/mocks/UserMockFactory.java
	deleted:    src/br/ufrn/dimap/pubshare/restclient/SaveUserRestClient.java