CLOUDIFY-2251

Mark that plugin installation is complete of a host using a variable and use this variable in the verification process to know when it should verify a specific plugin existence
CLOUDIFY-2251

1.host_init set a "agent plugin installed" state on the host using the kv_store plugin.
2.execute_operation will do a fast verification the existence of the plugin and its operation, if failed, it will wait until all plugins are installed by waiting for "agent plugin installed" state. once all are installed it will verify existence again, if failed it will raise an exception.
3. split plugin verfication and operation method argument fetching into two seperate operations.
CLOUDIFY-2251

Add test that an exception is thrown when an operation which the plugin doesn't implement is used.
ignore intellij project
CLOUDIFY-2251

- kv_store get operation added to task filter list.
- added debug logging showing the return result of the get agent installed plugin state in the execute_operation workflow
port travis yml fix
CLOUDIFY-2251 fix participant to handle get arguments task for relationship based operations
Merge pull request #96 from CloudifySource/feature/CLOUDIFY-2251_transfer_installed_plugin_knowledge

execute operation will now throw an exception if trying to invoke an operation which a plugin doesn't implement