Cancellation of leases.

Description

Adds cancellation support to leases.

This requires a new TenantManager which keeps track of running leases on bot, allowing for cancellation.

The various hardware classes have been refactored and moved to a new hardware/ folder.

Based on top of !106 (merged).

Changes proposed in this merge request:

• Simplifies state machine in the BotsInterface.
• Add a new TenantManager class for the Bot.
• Cancel leases on the bot.

This merge request, when approved, will close issue/bug:

#48 (closed)