Autoremove empty test cases in coding questions
New Feature: Lesson Plan will auto-open in current week
Initial commit of new rake task.
Complete rake task for adding existing achievements to FB as badges.

References Coursemology/coursemology.org#192.
Fix theme setting not functional bug
Check that facebook_obj_id in achievements does not exist before posting it to FB.

Only create a new 'badge' object on FB if its facebook_obj_id is currently NULL>

If not, assume the id is valid and don't do anything for this achievement.
As this task is primarily meant to be run once before achievements have
ever been posted to FB, nearly all of them should have facebook_obj_id is NULL.

References Coursemology/coursemology.org#192.
Add output statement for each created Facebook object.

Closes Coursemology/coursemology.org#192
Merge pull request #194 from fonglh/issue-192-add-achievements-to-fb

Add existing achievements to FB
Merge pull request #193 from wangqiang1208/bugfixing/theme

Fix theme setting not functional bug
Merge pull request #188 from wangqiang1208/bugfixing/coding-questions

Auto remove empty test cases in coding questions
Change TOZ grader pilicy
Refine implementation: consider next milestone's start_time as current one's end time
Merge remote-tracking branch 'upstream/development' into feature/auto-open-courseplan
add acts_as_sortable module
refactor assessment show to use act as sortable
refactor survey reorder with acts as sortable
reorder of achievement, fix #110
fill position of achievement upon creation
Merge pull request #191 from wangqiang1208/feature/auto-open-courseplan

New Feature: Lesson Plan will auto-open in current week
unique_attempts in answer.rb is not working, fixed