Update HOUSE2012_POLY to current shapefile

Here are the changes:
District Number: Previous Representative -> Current Representative
16: David B. Sullivan (D) -> OPEN
87: OPEN -> Wayne A. Matewsky (D)
131: Martha M. Walz (D) -> OPEN
36: OPEN -> Leah V. Cole (R)
135: Linda Dorcena Forry (D) -> OPEN
158: John P. Fresolo (D) -> OPEN

Using the Shapefile published by MassGIS:
http://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic-information-massgis/datalayers/house2012.html

and the conversion script: https://gist.github.com/jwass/6202165