CLOUDIFY-2116

Add test for validation of a dsl containing agent plugin without host relationship
CLOUDIFY-2116

Add validation to dsl that a node with agent plugin has a relationship contained_in a host node
CLOUDIFY-2116

Improve validation message
Merge pull request #74 from CloudifySource/feature/CLOUDIFY-2116-validate-node-with-agent-plugin-relate-to-host

Feature/cloudify 2116 validate node with agent plugin relate to host