Travis-CI IRC configuration

[Christopher <ct...@apache.org>]

#accumulo in IRC is getting some spam about continuously failing builds
from forks, such as this one:

https://travis-ci.org/mikewalch/accumulo/builds/360040017 (I don't mean to
call Mike out... it's just an example of a fork which is being updated and
triggering builds; the activity in his fork is a good thing... it means
he's working on features/fixes; the notices to the IRC room are the
unwelcome parts)

That's because it uses the same travis configuration... which, of course,
makes sense.
However, it's probably not useful. Does anybody know how to make Travis
only do the IRC notice if it built from the apache/accumulo repo, and not
in forks?

If not, perhaps disabling the IRC notification is best? (I'm not sure too
many people use IRC anymore... but no need to discourage further use with
extra notices from forks).

Thoughts?