Change relation between channels and streams

Updated specs and migrations
[Closes #45]
Changed stream structure

Changed title to caption and removed unused fields
Clean spec and unused routes

[Closes #44]
Added twitter gem to extract hashtags
Added logic to update channels from a caption

[Closes #43 #42]
Update migrations to support easy upgrading
Merge branch 'master' into caption-feature

* master:
  Add boxen support to databaseyml
Merge pull request #46 from peepoltv/caption-feature

Caption feature