Fix active threads endpoint

Previously, pagination was done before reducing from content to threads,
which meant that fewer threads than requested could be returned and that
the number of pages returned could be incorrect.

Return 404 instead of 400 when thread not found

Co-authored-by: Greg Price <gprice@edx.org>

don't require api key for heartbeat.

* don't require api key for heartbeat, nor expose tracebacks.
* add tests for heartbeat.
* fix test with hard tabs.

JIRA: FOR-96

reinstate disconnection from mongo in unicorn master thread

https://github.com/edx/cs_comments_service/commit/e61430d9438abf1db64fcac0eb9dd3e0f18a07bd was inadvertently lost in a recent change, this puts it back.

add heartbeat endpoint

use 404 when trying to GET a nonexistent user

JIRA: FOR-522

Adding additional config for production tcp listener

Working unicorn with env config.

Add test for sub-comment deletion

Add rake tasks for dealing with translations

Respect Accept-Language when getting strings

Update Transifex project name

workers from env, use socket

syntax change

temp hard code

path changes, debugging.

typo.

dynamic env.

more vars.

allow pagination of responses within thread views

JIRA: FOR-374

Make retrieving user's active threads faster

The user profile page in the LMS only displays the thread title and
body, not comments, so do not bother returning them.

set up transifex

use yajl for json serialization

Set up Travis CI

Add tests for non-ASCII characters in comments

Due to a bug[1] in ActiveRecord's JSON serialization, tests for characters
outside the BMP are marked as pending.

[1]: https://github.com/rails/rails/issues/3727