Plugin to remove spaces in hash

[ryanb]

This adds a plugin called strip_hash which removes spaces at the beginning and end of hash literals. For example, instead of { foo: "bar" } it generates {foo: "bar"}. This helps distinguish hashes from blocks and brings it more in-line with standard formatter. It is also similar to the deafult Prettier formatting for JS objects.

I understand if you want to keep the built-in plugins to a minimum. I'm just not sure how to accomplish this with an external plugin without monkey patching which is brittle.

Whatever the case, feel free to rename this, or reject it if it's not in line with the project.

Update: I renamed this from compact_hash to strip_hash to parallel String#strip method.

[kddnewton]

I think this is one of those where I want stree to be opinionated to limit the number of configuration options. But thank you for the contribution!