adds ability to use integer dates in data source

also updates cookie plugin check to look on jquery.prototype
reverts incorrect cookie check
slight performance improvement of for loops
fixes typos
adds new `isHoliday` function (not yet tested)
fixed up index.html (typos, bootstrap css upgrade, invalid markup, etc.)
code now uses `isHoliday` function (still needs testing)
updates reference jquery.cookie
fixes logic typo
added helper for holiday normalization
fix timing of call
add comment
Uses CSS positions instead of margins to position item bars.

Fixes taitems/jQuery.Gantt#13.
Re-fixes mousewheel scrolling in FF

Previous "improvement" from 2f6aabfa1d was incomplete in FF (at least)--my bad!
replaces deprecated jQuery.support.boxModel reference

jQuery.support.boxModel was removed in 1.10/2.0 .
See http://bugs.jquery.com/ticket/13743 .
Fixes bar alignment (related to #13 fix).
Removed top margin from bars since we don't need it.
updates moment.js to version 2.2.1
removes renegade quote in markup string

Note to self: the whole chunk of code here can probably be removed,
actually.. but that's for another pull request.
updated missed reference to old bootstrap css