Use the better supported offsetWidth property to get a fields width

Fixes #212
Update example page to show current default settings.
Merge branch 'master' into firefox-width-disparity

Conflicts:
	chosen/chosen.jquery.min.js
	chosen/chosen.proto.min.js
Merge pull request #1172 from harvesthq/firefox-width-disparity

Use the better supported offsetWidth property to get a fields width