Texas state scraper

Hi, here is a scraper for Texas state. It is pointed at the new bids page, but could also be redirected to the older bids page with minor modifications.  Thanks, Ed

$ bin/openrfps-test scrapers/tx/rfps.coffee
Cached results to scrapers/tx/rfps.json
The scraper returns at least one result: OK
item.id is returned for all items: OK
item.contact_email is a proper address (or blank): OK
download URLs are valid (or blank): OK
item.id is unique for each item: OK
item.title is returned for all items: OK
NIGP codes are digits: OK