asn: added header options and provider tests

only attempt to query providers that succeeded when we initialized.
asn: added spameatingmonkey as provider
asn: enable partly fixed routeviews lookups

the DNS fix in 0.10.26 partly fixes the c-ares bug, but only part of the TXT record is available. Hopefully node 0.11 exposes the rest of it
asn: added tests and minor tweaks

included an improved regex for parsing cymru