Rename learning target progress to concept progress internally.
Merge pull request #79 from graspapp/concept-progress

Rename learning target progress to concept progress internally. Closes #71.
learning_target_show_spec.rb -> concept_show_spec.rb
Merge pull request #83 from graspapp/authorization

Must sign in to access content. Also fixed alert background. Bootstrap c...
Concept controller now flashing error at appropriate time and not when user is logged in.
Revert "Concept controller now flashing error at appropriate time and not when user is logged in."

This reverts commit 07e06bba37ccbadf9ad73d0296470d1be9bfc167.
"Concept controller now flashing error at appropriate time and not when user is logged in. Fixes #84"