Merge branch 'pf-document-extensions'

Reviewed-by: Richard Maw
Merge branch 'master' of https://github.com/petefoth/morph

Reviewed-by: Richard Maw
Merge branch 'master' of https://github.com/petefoth/morph

This merges in more documentation improvements

Reviewed-by: Richard Maw
Add 'is_device' function to check if we are deploying to a device
Add force flag to 'mkfs.btrfs'

This way when deploying to a device it will format
it without asking the user if the device already
has format.
Don't loop mount when mounting a device
Split create_local_system on various methods

This way we can still use create_local_system to create
a raw disk, but also reuse bits of it to be able e.g. to
deploy to devices.
Modify rawdisk.write to allow the deployment to devices

This patch also modifies rawdisk.write to use the UPGRADE environment
variable to figure out when is doing an upgrade or a fresh deployment.
This change is important because os.path.isfile doesn't work with
devices.
Update rawdisk.check to support device deployments
writeexts.py: convert 'mount' to context manager
Merge branch 'baserock/pedroalvarez/rawdisk-to-device8'

Reviewed-by:
- Richard Maw
- Sam Thursfield
Fix line lengths to be shorter than 80 columns
Remove unicode characters
tests: Update expected git output
Merge branch 'baserock/pedroalvarez/fix-tests'

Reviewed-by:
- Francisco Redondo Marchena
- James Thomas