burnin: Remove temporary created files

Remove temporary files that have been created by the
Pithos TestSuite.
burnin: Update dependency on kamaki version '0.13'

Kamaki version '0.13' has added support for Synnefo projects (moving
resources between projects, allocating resources from a specific project
etc). In order for snf-burnin to test these functionalities, a newer
version of kamaki is needed.