Improved CDN and analytics

[BLooperZ]

Added global function for CDN fallbacks,
Modernizr is served with CDN as well (the cdn itsef can be changed)
Made use of it on the analytics snippet
(don't mind the "x-ua-compatible" yet, still on open issue: #1656)

pros:

• less characters:
  with modernizr fallback: 465 against 525
  without modernizr: 410 against 433
  (counted with the spaces in " || " removed)
• xml compatible (no document.write or something that look like an element)
• useful for make a fallback for any other script

cons:

• can't use b as variable in scripts - can easily be changed
• need testing to see if the analitycs snippet really works

[BLooperZ]

i updated the file to have only jquery fallback
still using the shorter analytics snippet,
please, consider the other improvements

[arthurvr]

This would make the jQuery fallback async, we don't want that. It might result in jQuery not being defined before other stuff gets executed.

[BLooperZ]

i think the jquery fallback is async either way (also in current version)

[mathiasbynens]

@BLooperZ <script>document.write('…');</script> is synchronous.