Bug 10861: (follow-up) use minlength/maxlength rather than pattern for client-side...

Bug 10861: (follow-up) use minlength/maxlength rather than pattern for client-side validation

This patch replaces use of the HTML5 pattern attribute with minlength
and maxlength, which is compatible with the jQuery validation plugin
and which, in Chrome 33.0.1750.146 at least, works better.

To test:

[1] Enter a new patron record or edit an existing one.
[2] Verify that the minimum and/or maximum length requirements
    set by the CardnumberLength syspref are validated and that
    form submission is prevented if the cardnumber doesn't
    meet the length requirements.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>