fix issues #48 and #49

Doing postComment, postLikeStatus on a message which actually does not
exist, returns an error.
Adding a field 'likeStatus' (its value is actually the one sent by the
user) in the JSON returned by postLikeStatus
Merge pull request #51 from SIMS-Topaz/hmu/fix_issues_48_49

fix issues #48 and #49