Added node_modules and minified JS skipping to .jshintignore

JSHint shows a number of errors for rickshaw, but I was able to cut out most of them by tweaking `.jshintignore`.

The rest look like this:

    $ jshint .
    examples\js\extensions.js: line 46, col 6, Missing semicolon.

    rickshaw.js: line 131, col 4, Missing semicolon.
    rickshaw.js: line 148, col 4, Missing semicolon.
    rickshaw.js: line 168, col 25, Unnecessary semicolon.
    rickshaw.js: line 184, col 29, Missing '()' invoking a constructor.
    ...
    tests\Rickshaw.Series.js: line 65, col 2, Missing semicolon.
    tests\Rickshaw.Series.js: line 74, col 2, Missing semicolon.
    tests\Rickshaw.Series.js: line 95, col 2, Missing semicolon.
    tests\Rickshaw.Series.js: line 113, col 2, Missing semicolon.
    tests\Rickshaw.Series.js: line 131, col 2, Missing semicolon.
    tests\Rickshaw.Series.js: line 149, col 2, Missing semicolon.

    59 errors

I left these alone for the rickshaw team to decide how to resolve.