Export Activity

 - Create export action for lightweight_activity controler.
Import Export Activity

 - Include the type of interactive and type of embeddabe in the export
json.

 - Add implement of import activity for admins.
Export activity UI

 - Add UI for exporting the activity.
Export function for Embeddables and Interactives

 - Add export functions for image_question and multiple_choice
Export functions for Interactives

 - Add export functions for image,video,mw interactive.
Export/Import functions for interactives and embeddabels

 - Add export functions for xhtml,video_source classes.

 - Add import functions for xhtml, open_responce, multiple_choice,
   image_question, image_interactive, mw_interactive, video_interactive.
Add styling for import popup UI

 - Add styling for import popup.
Display import button only for admin

 - Check if the current  user can perform import action.
Handle incorrect JOSN file

 - Display warning if the import fails or an attempt is made import
invalid json file.
Spelling and UI Changes.

 - Make the name of exporting activity bold.

 - Change the spelling of import, export button.
Authorize if the user can perform export

 - authorize export activity for current user
Rspec tests for export functionality

 - Test cases for exporting an activity.
Rspec tests for import lightweight activity

 - add test for 'imports page from json'

 - add test for 'should return an activity'
Rspec test for import controler

 - add test for routing 'recognizes and generates #import_status'.

 - add test for importing a lightweight activity.
Fix for test fail

 - imports page from json valid_lightweight_activity_import.json.
Merge pull request #27 from concord-consortium/import_export_activity

Merge "Import Export Activity" PR #27

I left some comments here, but it looks good overall. I will pull this now, and we can address the other issues as we continue to work.