Undefined method capture_message fixed

`sidekiq_retries_exhausted` is not able to invoke normal class method.
As a result "undefined method `capture_message` for
Atmosphere::VmTagsCreatorWorker:Class" was thrown. Fix introduces direct
invocation of `Raven.capture_message`.

To test this behavior I have also upgraded `rspec-sidekiq` into stable
released version 2.0.0

Fixes #11
Removed unused rake task, updated other

As a result only billing rake task remain.

Fixes #8
VMT version

Virtual Machine Template verion introduced. It will allow us to track
number of saves user performed.

Verion will be incremented only when it is not explicity set during creating
new VMT.
save action
remove older VMT action
remove old VMT action triggered after VMT state changed to ACTIVE