Bump src/loggregator

Bump :
  Matthew McNew:
     Revert "Removed the source type from the log message"
     Dont block message processing on error channel
     Adding invalid syslog drain urls to the blacklist cache
  Alex Jackson:
     Default the message buffer size to 100
     remove un-needed sleeps from test
     Fixing the readme to use the new gcf
     Updating the email list for travi notifications
  Matthew Koch:
     Trying to make the tests more stable for Travis by bumping up the timeout
     Trying to make the test more stable
     Removed the source type from the log message
  Casey McTaggart:
     Merge pull request #7 from cloudfoundry/buffer-update
  Johannes Tuchscherer:
     Make websocket buffer size configurable
  James Bayer:
     added detail about loggregator traffic controller