fixing mailchimp subscribe probz.
have to revert a bit of the async-ing in b8787f61d3a5280048d824ba68b7ce283bfa50c7.
fixes #449.
Merge pull request #453 from JoahG/master

Mailchimp Subscription Problems
update sentry-raven gem version to 0.12.2 for security patch
Merge branch 'master' of github.com:empirical-org/empirical-core
update Gemfile.lock to reflect new version of sentry-raven
Merge branch 'student-profile'

new student profile interface

 Changes to be committed:
new student profile interface
filter incomplete activity_sessions that correspond to retries