Two military men — one a senior at the Naval Academy, one an Army combat vet — hope to land a spot on a professional football roster this season. Then, if all goes well, you might never hear their names again. Joe Cardona of Navy and Nate Boyer of Texas both seek to join the fraternity of NFL long snappers — men who fire a football between their legs at north of 40 miles per hour and rarely receive any notoriety unless something has gone very, very wrong. Cardona is ranked atop the NFL.com special-teams prospect list. Boyer’s play at Texas and his inspirational story (Green Beret-turned-Longhorn who never played…