Authenticate the multiparty key if available

 * Warning: breaks backwards compatibility.

 * If there's a mp key for the user, add it to the secret when
   performing the smp. Detect if that key changes (or suddenly becomes
   available after authentication) and warn the user.

 * This definitely needs review.
Refactor smp answer preparation

 * Also, a more descriptive warning func name
Improve auth tutorial UI
Comment formatting
Fix bug with rendering of missing recipients warning
Fix image paths
Fix buddy list display bug for right-to-left languages
:3
Remove exaggerated warnings

This is no longer a young project.
Merge pull request #599 from arlolra/mp

Authenticate the multiparty key if available
Improvements to locale code
Merge branch 'master' of https://github.com/cryptocat/cryptocat

* 'master' of https://github.com/cryptocat/cryptocat:
  Refactor smp answer preparation
  Authenticate the multiparty key if available
Revert f5bbe8f..1208dc9

This rolls back to commit f5bbe8f6c773d90cd7161cecc870a33ce2653bf8.
Revert "Revert f5bbe8f..1208dc9"

This reverts commit 91db5866110cec53c752b8df8ddb5f2b99217608.
Re-add AKEWarning localization string

Also fix Travis
Fix locale unit test compatibility
Auth dialog fixes
Fix buddy list ordering
UI improvements
OCD