Add !glossary command

[zpatrick]

We need some sort of generic key/val storage command in our slackbot, similar to the !learn X as Y and !whatis X command in the current devbot. I think for all intents and purposes we can use a !glossary top level command with some subcommands:

# insert or update definitions using:
!glossary define KEY VAL

# remove a definition using:
!glossary rm KEY

# search for definitions using:
!glossary search GLOB

With search, the GLOB parameter should accept a glob pattern and display the matching key/val pairs, for example:

zpatrick: !glossary search fo*
iqvbot: **fork**: xxx
iqvbot: **food**: xxx
iqvbot: **fountain**: xxx

(with this, doing !glossary search * would return the entire glossary)

[zpatrick]

closed by #20