Fix incorrect width of .span* in IE6.

Width of grid in IE6 is not correct.

### Reason

There is a `.uneditable-input.span*` below `.span*`,  `.uneditable-input.span*` will overlay `.span*` for IE6 doesn't support *multiple class* like `.class-a.calss-b`.

### Solution

Use `.uneditable-input-span*` instead of `.uneditable-input.span*`.


### Commits

1. Fix incorrect width of .span* in IE6.
2. Add an test html to test grid
3. Build bootstrap-ie6