Implement email-scraper

Take the email scraper in existing weather and fix
minor issues resulting from integration.
Write bandwidth-candidates to file

Decrease verbosity of logging for possible bw
candidates, change to common logging-handler, write
candidate fingerprints to file.
Instead of writing to file, this can be easily refactored
to make use of a subsriber-database.
Fix formatting-bug in logging string
First sketch of welcome-script

This should check for relays qualifying for a welcome
email. Specification for this can be obtained from
https://trac.torproject.org/projects/tor/ticket/11084
Currently, we simply grab all stable-flagged relays
without checking anything, and attempt to deobfuscate
the contact-field.