FREEZR_CLOUD_BACKEND now used instead of freezr.backend.aws directly.
Unit tests now use the FREEZR_CLOUD_BACKEND instead of monkeypatching
freezr.backend.aws module.
Both regular tests and systemtests/run-fake-integration-test.sh now pass.

The fake integration test "fakes" EC2 state by replacing the use of
boto.ec2 connection with a custom one.
Added pre-push script to check that things pass as they should in
travis (see https://travis-ci.org/santtu/freezr/builds/15519548).

Also wondered for a long time why the pre-push script failed not
so deterministically. Finally figured out this was probably due to
a slow start of rabbitmq server due to log file growth.

'rabbitmqctl reset' took care of that, but also added wait loop
to freeze-thaw-aws.sh to wait until rabbitmq is answering before
proceeding (the failure was because POST to project tried to
issue account refresh, which could not be pushed to not-yet-responding
rabbitmq).
Trying to figure how to use rabbitmq in travis correctly.

See https://travis-ci.org/santtu/freezr/builds/15522146 failure.
Sigh, should have tested the log file output properly..
Hmm, of course. On OSX box rabbitmq is a brew installation, and not
being strict about uids, whereas travis' box is sudo'ed and strict
about uids. Let's see if using "sudo rabbitmqctl" works.
No virtualenv in travis, don't run unless found.
Hmm, countdown doesn't work on chains, only on an actual task in
celery. So, set kwargs on the task, and then chain it. (In task
dispatcher.)
Virtualenv activate isn't executable, but readable.
Various changes.

* On project region update, delay the account refresh a little. Before
  this allowed the task to be run before the updated project was
  saved in database, causing it to be omitted from being moved
  from init state to running. (For some reason, this error manifested
  more readily on linux instead of osx -- process scheduler?)

* Also increased leniency of the celery consumer reconnect policy. This
  caused one error in about 4-hour repeated fake systemtest run. (Why
  rabbit wasn't responding is another interesting question..)

* Removed direct systemtest test case dependencies on freezr modules --
  don't use freezr.util.Logger mixin, don't use backend's connect_ec2
  but go back to boto. The one dependency needed is freezr.backend.tasks.

* Some minor formatting etc. fixes.