Eoin add domains script

Added a script to generate the "domains = ..." regex from the IANA maintained file at http://data.iana.org/TLD/tlds-alpha-by-domain.txt. (I didn't add any tests because it's a small script which has to be manually copy/pasted anyways--it's otherwise never actually used in code.)
for pylint, prefer the name of the thing you're disabling.  pylint allows you to use the string for the name

like `# pylint: disable=line-too-long` (idk if this is actually what it is named, but it is human readable instead of machine-readable) :)