patching the parsing of specified currencies in BidRequest.curr
adding parseISOCurrency(). still broken; BidSwitch
passes testing with Ipponweb
added bidswitch_exchange_connector_test
Merge branch 'BIDSWITCH' of https://github.com/jsulmont/rtbkit into jsulmont-BIDSWITCH

Conflicts:
	plugins/bid_request/openrtb_bid_request.cc
Removed duplicate currency parsing code
Merge branch 'jsulmont-BIDSWITCH'