calculate outerWidth before wrapping the input element

In some cases, like when the input element is given a percentage width,
wrapping the element makes `.outerWidth()` return 0 (or 2px, if it has a
1px border).  Calculating the original width before wrapping the element
prevents this.
Merge branch 'bugfix.outer-width-before-wrapping' of https://github.com/jayferd/jquery-textext