Ignore focus and error on IE7 for disabled select2

For disabled components, focus event was triggered.
On modern browser this error was ignored but not on IE7.

This PR save weird focus event and IE7 JS error.
Add text function for formatResult and formatSelection
Remove added line
IE and compat mode :/

Fixed 2 minor typos which prevent select2 to work in IE compat mode.
only switch right to left drop when enough room available
Added initial contributing guidelines
Add IRC information to README
Fixed a few links
Issue #2412

Maybe the fix is a bit ugly, but what it does is to make sure that we don't already have a select2-hidden-accessible span before we create a new one. Tested in several scenarios in our application and has solved the issue for us.
Merge pull request #2227 from fabdouglas/patch-6

Ignore focus and error on IE7 for disabled select2
Merge pull request #2609 from ivaynberg/issue_1535_contributor_guidelines

Add contributing guidelines
Merge pull request #2610 from torke1/patch-1

Prevent multiple select2-hidden-accessible span's
Merge pull request #2591 from gsirin/patch-1

IE and compat mode :/
Merge pull request #2595 from scotam/drop-left-check

Adds check for enough room before switching right to left drop
Merge pull request #2415 from santialbo/text-function

Add text function for formatResult and formatSelection
Add cdnjs to the README

This closes #2638.
Fixed JS breakage due to undefined variable, viewPortLeft.
Merge pull request #2642 from b4oshany/master

Fixed JS breakage due to undefined variable, viewPortLeft.
Remove UTF-8 BOM

select2_locale_ar.js (and only it) contains the UTF-8 BOM: let's remove it.
Merge pull request #2650 from mlocati/remove-utf8-bom

Remove UTF-8 BOM