Fixing a bug that will allow a value of '0' to bypass validation.

[leadoux]

Hi Matt. We use your gravityforms-regex-validation plugin - thanks. I have found a small bug where a value of 0 will not pass as True for !empty($value), and then regex validation does not happen, allowing '0' to pass strait past the regex - obviously not a desireable outcome. Please reveiw my simple fix and consider rolling it into your code to fix this issue for all. Regards...Adam.