Rename all Plugins .help to .commands.

commands is more descriptive of what we are doing, and
.help is also matched by cinch itself so we were getting
odd "#<PluginCommand:0x9cd897c>" output from cinch's
internal help handler.
Fix context/it statements for .commands.
Merge pull request #24 from rjackson/move_help_to_commands

Rename all Plugins .help to .commands. (Take #2)