Fixes Issue 125 - Hanlon client config contains unnecessary parameters

After separating Hanlon into cli and web components, we created hanlon_client.conf to manage client side configuration parameters. Most of the parameter belonging server side logic are removed from client config except for image_path and persist_xxxx set. Client code models were using parameter due to entangled code where client is implementing the code logic or server and client code blocks are placed in single file. To remove these parameters we needed another code refactor which is addressed in this pull request.

This pull request completely removes the above said parameters by...
*. Removing db interfaces where not required and isolating the dbinit to server line of code execution
*. Removing cli/hanlon config db_check command which is not required at client end
*. Moving local image path building logic from client end to server
*. Extending hanlon image rest api end point by adding local_image_path parameter

The lines you are commenting out here, @sankarvema, are in place specifically to handle the edge case where there are no tags associated with a node. In those cases, these two lines will set the tags for the node to the string `n/a` in order to avoid an exception when the `join` method is called to join the tags together as a string. I don't think we should be making this change.