adds ability to use integer dates in data source (plus various fixes, enhancements, and housekeeping)

Now a date can be of the following valid forms: `"/Date(1378232692170)/"`, `"/Date(2013/09/03 20:24:52)/"`, `"2013/09/03 20:24:52"`, `"1378232692170"`, or simply `1378232692170`.

Using numbers is generally more efficient and consistent than strings in JS (especially in this case), plus it reinforces a cross-browser, cross-platform standard thus avoiding many potential pitfalls related to date string format parsing.

Also:
- fixes #56 (holiday format inconsistencies)
- fixes #13 (use CSS positions instead of margins for bar positioning)
- fixes #38 (empty array source causing error)
- re-fixes mouse wheel scrolling in FF (formerly broken by me in 2f6aabf)
- replaces deprecated (removed in 1.10/2.0 !) `jQuery.support.boxModel` reference
- fixes some typos and minor markup issues in index.html
- updates reference to bootstrap CSS to current version
- upgrades reference `jquery.cookie` plugin to current version
- upgrades moment.js plugin (used in tests) to current version
- minor performance improvements of `for` loops ([as recommended](http://taitems.github.io/Front-End-Development-Guidelines/#javascriptLoopCacheArrayLength) by @taitems).

**Does not yet include** updated examples and documentation, nor minified js file. All of these can be done after merging into the develop branch, but they should & will be done before merging into the master branch.