Review Composer: Base Foundation Restructuring

Review Request #10210 — Created Oct. 9, 2018 and updated — Latest diff uploaded

Review Board
reviewboard, students

In this commit, the references to ReviewDialog
in the codebase were renamed to ReviewComposer.
The exceptions to this are the ReviewDialog references
that have to do with extensions. There were slight
format changes made to the header and footer. The
icon for the ShipIt checkbox was added but there is
some CSS that needs to be added in to make the toggling
between checked/unchecked icons to work. The comments
also still need to be restructured.

I ran the Javascript Unit tests. The 6 test failures are the same as the ones in the master branch so the changes seems to have not broken anything.