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.