Frontier Airlines said Friday that there is an increasing number of people who are abusing the carrier's wheelchair system in order to get priority boarding.  "There is widespread abuse among passengers using wheelchair services to move to the front of security lines and obtain priority boarding on flights," the carrier told FOX Business, adding that "the TSA and airlines are in a difficult position when it comes to managing the issue." The statement comes on the heels of Frontier CEO Barry Biffle's comment ...