Add server plugin

Add server type definition.
Add implementation for vapp create and delete.
Add common code.
Add integration tests

Add integration tests common code and
example configurations.
Add server plugin tests.
Add server start and stop operations.
Add server plugin
Add files for network plugin
Rename file
Add functions stub to floatingip.py. Add nodetype and relationship to plugin.yaml
Add small changes
Merge branch 'nat-develop' of https://github.com/achirko/tosca-vcloud-plugin into nat-develop

Conflicts:
	server_plugin/server.py
	vcloud_plugin_common/__init__.py