Multi endpoint

This pull request is patching the openstack components as the result of a scale-up test on cc.in2p3.
Additionally, some VM dirac configuration parameters treatment have been change to be configurable by the CS Endpoint info: siteName, CPUTime, cloudDriver (instead of Contextualization) both on OpenNebula and OpenStack images and drivers. As CloudStack is ad-hoc image this features are not part of it.
It is also fixing non previouslly test bugs from other branches.
Please, merge this pull request before than #32,  this one is more stable as the nova user_data (amiconfig) is an new feature. The current pull request has been certified with 2K jobs without errors and 220 VMs running at in2p3, pic and usc.
Latter #32 can be merged and as new feature it should be straight forward.
Thanks