1. Removed duplication of code in stage component to avoid future
     potential divergence. Now just selectively applying styling based
     on states of zoomed, colorPicking, and question.

  2. Fixed bottom border getting chopped in zoomed mode by adding margin
     and adjusting height/width accordingly.

  3. Removed shouldComponentUpdate from stageHeader as suggested from code
     review. Added ignore lint warning suggesting change to stateless function.

This is for https://github.com/LLK/scratch-paint/pull/194, making the selector area smaller on tablet so as to create more space for the paint editor

* removed anything that was made redundant by scratch-l10n.
* updated a string that wasn’t following conventions
* added .tx/config so developers can start updating Transifex when there are new strings

Changed existing string ids to use the convention `<repo>.<component>.<identifier>`

Alphabetize all the things

  Commit fceba4e8 introduced new sizing behavior for the stage in
  order to fit everything in a 1024 width. Adopted this same behavior
  for the StageHeader component.