Update thumbor-worker Upstart job

Removed enabled=1 check, as you can just use `update-rc.d enable|disable` for that purpose (or add `exit 0` to the default file). Changed instance variable to be more meaningful. Removed bad usage of /tmp (it was unsafe and allowed escalation to root).
Updated thumbor upstart job

Removed check of enabled=1 (see previous commit), renamed port var to ports, adjusted start/stop events slightly.
Changed port to PORT, since default files will override the variable
ports went back to port, so default files do not break
Add http loader configuration keys for cacerts and client ssl
Fix #346. Support for optimizers. Included jpegtran as example implementation.
Release 4.5.0
Fixing to only process jpeg files
Release 4.5.1
Removing jpegtran as the default optimizer
release 4.5.2
Fixing issue with file not being closed before being read by jpegtran
release 4.5.3
Remove pdb
Merge pull request #361 from mattrobenolt/pdb

Remove pdb
sentry_error_handler_vows: Fix 'Sentr' -> 'Sentry' typo

This dates back to the creation of this vow in 44c432d2 (Error handler
vows. 100% covered now, 2013-03-28).
Merge pull request #363 from wking/sentr-sentry-typo

sentry_error_handler_vows: Fix 'Sentr' -> 'Sentry' typo
.travis.yml: Don't install distribute

http://python-distribute.org doesn't seem to be up anymore, which is
not surprising so long after the Distribute/Setuptools merge of
2013-06-01 [1].  This reverts 3b41da8d6 (Fix travis CI builds,
2014-02-04).

Instead, we run 'make setup' with sudo to avoid:

  $ make setup
  ...
  error: invalid command 'egg_info'

[1]: https://pythonhosted.org/setuptools/merge-faq.html#what-is-the-timeframe-of-release
vows.mongo_storage_vows: Set a server in GetNothingAfterExpiration

Avoid:

  Traceback (most recent call last):
    File "/.../pyvows/runner/gevent.py", line 104, in _run_setup_and_topic
      topic = topic_func(*topic_list)
    File "/.../vows/mongo_storage_vows.py", line 210, in topic
      storage.put(IMAGE_URL % 10, IMAGE_BYTES)
    File "/.../thumbor/storages/mongo_storage.py", line 39, in put
      if not self.context.server.security_key:
  AttributeError: 'NoneType' object has no attribute 'security_key'
Merge pull request #365 from wking/mongo-vow-get-nothing-server

vows.mongo_storage_vows: Set a server in GetNothingAfterExpiration