Authorizing real estate taxes for the City of Philadelphia and the School District of Philadelphia for Fiscal Year 2013 and thereafter, by amending Chapter 19-1300 of The Philadelphia Code, entitled "Real Estate Taxes," to provide for a tax and tax rate on real property, for exclusions, and for an established predetermined ratio; and by amending Chapter 19-1800 of The Philadelphia Code, entitled "School Tax Authorization," to further authorize the Board of Education of the School District of Philadelphia to impose a tax on real estate within the City of Philadelphia, and providing for a tax ra — Open Common Ground