Wait for a numeric on IRC notifications

Code originally by Nick Markwell (@duckinator), ported to the current
codebase by me. This is a port of the code in travis-ci/travis-core#56.
Remove unnecessary line

If we refer to @numeric_received when it's not initialized, we'll get
nil back, and since we just need a falsey value, that's enough.
Search for repos by github_id on user sync
Update owner_name and name on repository sync
WIP: New build email.
Fix tests, improve email details.
Use assets host for email images.
Delete old build email files.
Use https for assets.
Create unique index on repositories(github_id)
Add url_options.
Specify proper URLs for img elements.
Style link in the build email header.
Fix styles to be more specific.
More email style fixes.
Lawl, email?
Set a proper width for the footer.
remove the log services as they now live in travis-logs
Fix footer width.
no need to register something which no longer exists