Fix z-index on input text box for single selects.

Using the select2 control in a jquery dialog works fine except for you cannot click on the input box when doing a single select select box. The containing div was given a z-index, but not a position attribute, so the z-index was ignored.
Merge pull request #431 from gladmon/master

Fix for z-index of search text box on single select
mange disabled attr on source element. fixes #427
trigger blur handlers on source element when select2 is blurred
original option not available to formatSelection on init

The original option isn't available to formatSelection when initializing the selection from a select[multiple]
Merge pull request #432 from brettmas/master

make original option available to formatSelection on init
formatSearching can be disabled

formatSearching can be disabled by returning null from the function which allows the searching message to be disabled.
Merge pull request #434 from hzy-/master

formatSearching can be disabled
relax formatSearching check. #434
pass element attr to initSelection for selects upon init
Use single quotes for retina image url

This is how all the other images are being referenced.
Merge pull request #443 from lunks/patch-1

Use single quotes for retina image url
Fixed placeholder detection.  Fixes #424.
Merge pull request #444 from kevin-brown/master

Fixes 424: Improved Placeholder Detection
fix tab index issues. fixes #408
Add support for GPL 2

Modify the text to include support for GPL 2
Add licenses text.
Merge pull request #464 from ericandrewlewis/master

Add dual-licensing support for GPL 2, which is incompatible with the Apache License
update license in js header
Add license text changes to README