Downgrade to PyYAML>=3.10, Upgrade pyvcloud to pyvcloud>=13rc12 for fix conflict with cfy 3.3m1
Downgrade to PyYAML>=3.10, Upgrade pyvcloud to pyvcloud>=13rc12 for fix conflict with cfy 3.3m1

cloudify-cosmo/tosca-vcloud-plugin,kemiz/tosca-vcloud-plugin,denismakogon/tosca-vcloud-plugin