Fix reference of resource-modify option
burnin: Don't attach two NICs to public networks

Burnin used to attach two NICs to public networks and test that the
virtual machine is accessible through both NICs. This test used to fail
because the virtual machine has only one gateway and the firewall
doesn't allow traffic that comes from one NICs to be routed through the
other.

Remove the above test and instead first detach the virtual machine from
the public network and then re-attach it (hence test hotplugging
functionality).
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.
docs: Update {index,cyclades,pithos}.rst for v0.16

Update index, cyclades and pithos general documentation to reflect
v0.16 changes, most notably:

 * Implementation of the Volume Service and Cinder API
 * Integration of Archipelago as the only Pithos backend
docs: Add storage unification document

Add a new storage unification document describing the relations
and workflows between Objects, Images, Snapshots and Volumes.

Also reference it from the index page.
astakos: Fix ASTAKOS_IM_MODULES typo in stats

The correct setting to be used is 'IM_MODULES' and not
'ASTAKOS_IM_MODULES'.