Initial version of GSA IG report scraper
Fixes for GSAIG scraper

Parse dates for more documents, add hardcoded dates for old documents without
dates.
Ignore pagination links when looking for reports
Handle relative URLs
Also look for MM/DD/YY dates in non-link text
Add year range handling to GSAIG
Misc. fixes to GSAIG
Merge pull request #29 from divergentdave/gsa

GSAIG scraper