added obsolete territories

Added is_obsolote_territory field, added three rows for Dakota,
Orleans, and Philippine Island territories (many other obsolete
territories exist (often precursors to statehood) and future additions
may be in order. These three were selected due to the fact that (as far
as I can tell) they were the only three which sent representatives to
cognress)
updated is_obsolete_territory field name

changed to is_obsolete
update gitignore

to include .DS_Store
Merge pull request #2 from bchartoff/master

added obsolete territories