IE8 Bug fix, added _wrapInnerContent method to prevent duplicate code, added missing call to "callback" option if defined, some code reformatting.

- IE8 Bug fix (issue #1)
- Added _wrapInnerContent private method to prevent duplicate code
- Added missing call to "callback" option if defined
- Some code reformatting
- Updated readme to list "pagingSelector" option
- Updated to version 2.1