[STAR-2453] Documentation and Patcher Improvements

This MR fixes an issue with patcher state instantiation-- forcing creation of patcher states upon setting x on a single module, so that redundant updates need not be made, and Redux doesn't complain about modifying state for a single module when accessing the patchers on a Single Controller.

This MR also updates the documentation to make it clearer what benefits Providence is providing.

JIRA tickets: https://tasks.opencraft.com/browse/STAR-2453

Testing instructions:

1. npm install
2. make qa

Once you've verified the code changes, destroy the dist directory, enter the docs directory, run:

1. make install_prereqs
2. make run

...And browse the documentation.