--allow-all-external is required for pip

At least one of the packages, argparse, is currently can't
be installed by simple 'pip install argparse==1.2.1'. To be
able to install it from external sources, --allow-all-external
option to pip can be used

Change-Id: Ib7199dca14b9bf471fb986b3ef4b805d22372a09
Closes-Bug: #1299678
Merge "--allow-all-external is required for pip"
vCenter integration UI added
removed kvm and qemu hypervisors for custom CentOS release
changed the vcenter UI, added dependencies, removed separate release
vcenter integration UI refactored
added dependency. neutron option will be not available with vcenter