http-info can ignore specific users

With other notifications from scripts, and links to private GitHub
repos, this script can get pretty noisy.

Added HUBOT_HTTP_INFO_IGNORE_URLS to exclude urls by RegEx
Added HUBOT_HTTP_INFO_IGNORE_USERS to exclude users in a list

Control the noise by excluding users, or regex matches on notification
text or both
Merge pull request #680 from Iristyle/httpinfo-ignores

Http-info now accepts environment variables to ignore more urls