Make use of the new generator functions in machine class

Switched to using generators for some of the simple methods
to get rid of those temporary lists.

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>
use generators for querying all machines

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>
Use machine generator

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>
Add a few setters and class inspection strings

Allow us to override memory, storage, and cpu counts. This is mainly
for when we query maas changes as juju does not aquire those hardware
specs.

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>
combine parse_state to one query step

Since the addition of the Machine() class we dont have to check
for multi or single systems when querying machines viewable
by juju.

Also comment out the maas section as that's not really needed in the nodelist

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>