State or diagnostic command

[TylerConlee]

Add @slab state, which DMs the user a list of the Sent notifications slice

[TylerConlee]

In order for the sent slice to be accessed, it has to be bubbled up to the main package to avoid creating an unnecessary dependency from slack to zendesk. The slice in question is already being exported in zendesk. It just needs to be set in process.go during the loop after the cache updates. Once sent is brought into the Slack package, it should just be a matter of outputting that to a message.

Other options for output include:

• number of tickets parsed in last loop
• number of tickets with SLA parsed
• last loop time

[TylerConlee]

Initial message in #104

Changing to Bug as the sent slice output is [{7302 5 323031382d30322d30352032323a32303a3539202b3030303020555443}] instead of readable text

[TylerConlee]

#105 broke things as the interface wasn't properly type asserting, #108 reverted those changes.