Require all *.rb files under plugins, and use PluginHandler to set cinch plugins.
Rework help system (again) to reduce channel noise.
Make github automated status less noisy.

* Only print the status if the current status is worse than 'minor'.
* Only print the status if the current status is different than
the previous message.
Update expected help message.
Update help_example image and README.
Update help output to use multiple matchers print out an ASCII table.
Revert changes to turbot.yaml.
Merge pull request #19 from rjackson/use_plugin_handler_to_set_cinch_plugins

Require all *.rb files under plugins, and use PluginHandler to set cinch plugins.
Merge pull request #21 from rjackson/reduce_noise_for_github_plugin

Make github automated status less noisy.
Merge pull request #20 from rjackson/rework_help_to_reduce_channel_noise

Rework help system (again) to reduce channel noise.