[#11] Add a system for scripts to add help and the bot to retrieve and display it.

- Adds bot.help API that can be used to add and get specific help text,
  and a summary option to retrieve a list of all registered help texts.
- Adds a script that interfaces with the bot.help API in order to allow
  for display of help message by the bot itself.
- Provides basic documentation for adding  help text to your own scrips.
[#11] Remove unused util library requirement from help.js.
[#11] Simplify instantiation of Help object.
[#11] Move library files to the npm standard /lib instead of /src.
Merge pull request #29 from Lullabot/11-help-api

[#11] Add a system for scripts to add help and the bot to retrieve and display it.