merge David's new string constants.
Merge remote-tracking branch 'upstream/master'
Merge pull request #37 from topcircler/master

Refine string constants on behalf of David
support anno insert/merge/get/list
change url param type to avoid error on app engine environment.
Merge pull request #39 from topcircler/master

Initialize anno backend service using google cloud endpoint; Implement REST apis for anno entity.
1. support 'projection' by select clause in url;
2. change 'comment' property name to 'anno_text' to avoid ambiguous.
Merge remote-tracking branch 'upstream/master'
Merge pull request #40 from topcircler/master

Support 'projection' for anno entity; change 'comment property name to 'anno_text'.
Added api for copy db tool
Added copy db tool
Merge pull request #41 from SergeyGadzhilov/master

Added api for copy db tool
1. return user information during anno get;
2. CRUD of vote/flag/follow_up.
Merge pull request #42 from topcircler/master

1. return user information during anno get;2. CRUD of vote/flag/follow_up.
1. return is_my_vote(true/false),is_my_flag(true/false) in anno.get api;
2. return followup_list in anno.get api.
Merge pull request #43 from topcircler/master

1. return is_my_vote(true/false),is_my_flag(true/false) in anno.get api;
1. support screenshot download.
Merge pull request #44 from topcircler/master

support screenshot download
support vote/flag delete operation by anno_id.
Merge pull request #45 from topcircler/master

support vote/flag delete operation by anno_id.