test: Set up JSHint and pass it

Violations:
* cssjanus.js: line 37, col 41, Bad or unnecessary escaping.
* cssjanus.js: line 159, col 4, Mixed spaces and tabs.
* cssjanus.js: line 133, col 45, 'Tokenizer' is not defined.
* cssjanus.js: line 134, col 44, 'Tokenizer' is not defined.
* cssjanus.js: line 135, col 40, 'Tokenizer' is not defined.
* cssjanus.js: line 215, col 19, 'Tokenizer' was used before it was defined.
* cssjanus.js: line 23, col 17, 'prepared' is defined but never used.
* cssjanus.js: line 245, col 39, 'token' is defined but never used.
* cssjanus.test.js: line 244, col 71, Strings must use singlequote.
* cssjanus.test.js: line 245, col 65, Strings must use singlequote.
* cssjanus.test.js: line 248, col 75, Strings must use singlequote.
* cssjanus.test.js: line 249, col 69, Strings must use singlequote.

Changes:
* Fix style violations.
* Made Tokenizer not a global variable but a local function, like CSSJanus.
* Swapped Tokenizer and CSSJanus to make it clearly defined
  before the first reference to it appears.

Fixes #14