Added isOwner policy

[Tenkir]

Checks if the user is the creator of the target object, or is an admin.Returns a 401 or 403 error if not.

[tarlepp]

This one I really like, thanks! But there is some minor changes that I would like to see before I accept this one.

• Change .exec() to use promises
• Handle errors within promise .catch()
• Add policy to all update routes
• Use sails ActionUtil to parse model and id example
• Check this style guide for code format

Also I'm thinking of isAdmin policy that could be attached to create routes. And another thing is assoc handling (add to and remove from) with this policy or a new one.

What are thoughs about my comments?

[tarlepp]

Any progress with this?

[tarlepp]

Any progress with this?

[tarlepp]

Any progress with this?

[tarlepp]

Any progress with this? Going to close this one if replies won't come.

[Tenkir]

Well this PR needs to be closed anyways since the front and backend have been moved into submodules.