Fix for #1411 and #1407. Corrected the malreferenced variables, was not able to verify #1407 as being fixed since there wasn't clear instructions on how to replicate.

Update message pinning to show up on the tab list with a few options to allow/disallow it and whether to allow anyone to pin messages

This change also alters how edits are displayed both for sequential
and non-sequential messages.

See #1357

Added user method for searching users from same domain

Users model findOneByEmailAddress had a typo in the query field.  The
following use cases are fixed:
1. sendConfirmationEmail
2. sendForgotPasswordEmail
3. lookup existing admin by email when initializing RocketChat at
startup