Relax JSCS code style rules and include checks in build

- Remove checks for variable and field names, some APIs demand
  underscores in names
- Remove check for spaces after "//" in line comments, as this prevents
  commented code blocks
- Allow for quoted keys in objects, as keys with special chars in them
  must be quoted and mixing quoted and unquoted keys can be confusing

Fix all remaining code style issues.

Use npm module "grunt-jscs" instead of "grunt-contrib-jscs", despite
the established naming pattern, the latter seems to be unmaintained and
does not support .jscsrc files.

Change-Id: I45e040384637cac22027a7fcdd734a9df358e89b