Rewrite how we handle configuration in env

env.conf --> env.conf.wiki, env.conf.parsoid

We now have some pretty nice-looking config objects, and they're being used
everywhere.

(bug 42841) Also, move the default config into an actual javascript file so we
can require it by default, in case the real one doesn't exist.

Tests:

/.../js/tests$ node roundtrip-test.js "Barack Obama"
=====================================================================
=====================================================================
SUMMARY:
Semantic differences : 0
Syntactic differences: 0
---------------------------------------------------------------------
ALL differences      : 0
=====================================================================
=====================================================================

9988 total passed tests, 4435 total failures (no change)

Ran Parsoid service locally and roundtripped Barack Obama in French,
works as expected.

Ran VisualEditor on a local wiki and was able to make edits without any
issue.

Change-Id: I5537708689f55d6651bac1aba5a8d4bdf8df6f7f
Merge "Rewrite how we handle configuration in env"