Add spec for locating button elements by :value + Regexp.
Add spec for locating button elements by :value + Regexp.

This was a regression in watir-webdriver 0.6.5

titusfortner/watir,titusfortner/watir,watir/watir,abotalov/watir-webdriver,watir/watir,titusfortner/watir-webdriver,titusfortner/watir,titusfortner/watir-webdriver,jkotests/watir,jkotests/watir,titusfortner/watir,jkotests/watir,abotalov/watir-webdriver,jkotests/watir-webdriver,jkotests/watir-webdriver,jkotests/watir,abotalov/watir-webdriver,abotalov/watir-webdriver,watir/watir,watir/watir