build: Update jscs and use new "wikimedia" preset

Our coding style has been upstreamed as of
grunt-jscs-checker v0.6.0 (node-jscs v1.5.0).

The validateIndentation and disallowQuotedKeysInObjects rules were
not previously enabled here. Fixed the few indentation violations
and surpressed disallowQuotedKeysInObjects for now (we can do
that later).

Remove the coding style check for dist/. Trying to maintain
indentation and other style rules there doesn't seem useful.

Change-Id: I96bca81ff6edd3f9dc29129402ed37f0b508ce87