Changes to ObjectStorage Client

* Changed signature of create_formpost by
  adding optional parameters signature,
  x_delete_at, and x_delete_after.
* Changed form_post method to be able to
  handle the new parameters.
* Fixed PEP8 style issues

Change-Id: I02d16ef2032c785fca39ce7ffc603d0a3a516c38
Merge "Changes to ObjectStorage Client"