Merge branch 'hotfix/api_nested_comments'
Merge branch 'release/1.1.0'
reorganize configus to add mailer settings
add user mailer
add rails-observers gem
add observer for user model to send emails
Merge branch 'release/1.2.0'
Merge branch 'feature/mailer' into develop
Merge branch 'hotfix/1.2.1' into develop