Remove "organization", "communication" and "miscellaneous" app groups

Summary:
Merge "Organization" and "Communication" into "Core". The split between these three was always tenuous, and this is easier to use and nicer looking on the new launcher.

Merge "Miscellaneous" into "Utilities" since they're basically the same thing.

Test Plan: Looked at app launcher.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9334