Ron Boltz has used up many vacation days to roam the halls of the state capitol in order to meet legislators and convince them to get rid of the state property tax.   He says his group, Pennsylvania Liberty Alliance, wants to replace the property tax with a broad-based tax that preserves current school funding levels, and citizens' property rights.   Mr. Boltz is planning to deliver 30,000 signatures on a petition to the governor calling for the elimination of the property tax.