settings: add configuration for pool of instances

Related to #26.
settings: fix syntax

Looks like I'm stupid.
api/models: add alloc method

This method will create the database in a provisioned instance.

Related to #26.
api/models: add dealloc, for deallocating pre-provisioned instances

Related to #26.
all: fix flake8 reported issues
api/views: revert accidental change in previous commit
api/models: set instance state to stopped

Related to #26.