Readme OCD fixes.
Add Select2 v3.2.5 to the demo/docs pages.
Remove a "known issue" from the readme.

The issue itself was fixed in Bootstrap 3 somewhere along the way from v3.0.0-RC to v3.2.0.
select2-bootstrap3-css makes use of Bootstrap's own variables to define the height of elements; select2-bootstrap3-css v1.4.0 was the first version not built on Bootstrap 3 RC, but on Bootstrap v3.2.0 – the update of the underlying Bootstrap version resolved the issue.
Remove gradient for IE <= 9; really fixes https://github.com/t0m/select2-bootstrap-css/issues/35; bump version to v1.4.3.
Merge pull request #57 from fk/bootstrap3

bootstrap3 v1.4.3