CYB-271 Support for number of views of Gallery items

Support for tracking views
  * new model, controller, route for views
  * gallery controller will return 'views' count(actually implemented in lib/array_refinement and
     in the attachment and media_url models)
Merge pull request #170 from coyote/track_views

CYB-271 Support for number of views of Gallery items
CYB-280 - Front-end - show views / increment views / sort by views

https://jira.ets.berkeley.edu/jira/browse/CYB-280
Merge pull request #171 from christianv/CYB-280

CYB-280 - Front-end - show views / increment views / sort by views
CYB-281 - Sections not displayed in Leaderboard: backlog the feature, task: remove column and filter in

https://jira.ets.berkeley.edu/jira/browse/CYB-281
Merge pull request #172 from christianv/CYB-281

CYB-281 - Sections not displayed in Leaderboard: backlog the feature, task: remove column and filter in
CYB-285 - Link from name instance to gallery pre-filtered by name

https://jira.ets.berkeley.edu/jira/browse/CYB-285
Merge pull request #173 from christianv/CYB-285

CYB-285 - Link from name instance to gallery pre-filtered by name
CYB-272 Item submitter gets points when another user comments on item

  * Returns HEAD 201 CREATED when a comment is created, whether or not
    the comment poster is credited points (done only if not the original poster).
  * Returns HEAD 204 NO CONTENT when a comment is updated.
Merge pull request #175 from coyote/comment_credit_for_original_poster

CYB-272 Item submitter gets points when another user comments on item