Allow hubot to react on events

Events might get triggered by scripts.

For example: You have a script, which can trigger and event that some one committed to a repo. This script can be used by anyone, but the reaction should be different by every company. So it's possible to trigger a build, or just post a message in chat.

As a plus with the same event triggered by different scripts, so it wouldn't make a difference if you commit into github or just another (maybe SVN) repo. But other scripts can rely on that 'commit-received' command and act the same way.
added docs for event system
Allow hubot to react on events

Events might get triggered by scripts.

For example: You have a script, which can trigger and event that some one committed to a repo. This script can be used by anyone, but the reaction should be different by every company. So it's possible to trigger a build, or just post a message in chat.

As a plus with the same event triggered by different scripts, so it wouldn't make a difference if you commit into github or just another (maybe SVN) repo. But other scripts can rely on that 'commit-received' command and act the same way.
added docs for event system
examples and fixed documentation for event system
Merge branch 'events' of github.com:nesQuick/hubot into events

Conflicts:
	README.md
	src/robot.coffee
Updated method headers

to make them more understandable. see https://github.com/github/hubot/pull/344#discussion_r3017158
Merge pull request #344 from nesQuick/events

Allow hubot to react on events