Get the user in a more robust way.

'os.getlogin' doesn't work for Jenkins - getpass.getuser() should
mksquashfs will, by default, append rather than replacing. This is a
bad plan in our context, so remove the target file before we start to
stop it doing so.
Also check the *ordering* of CPIO creation

That is, the order in which roles are used should determine which
files are chosen when there is more than one file of the same name.
Remove deprecated functions from deployments/cpio
Make Instructions responsible for printing themselves
Make it explicit what we need root for
A first test for collecting deployments
Ordering tests, and the support commit I forgot
Fix typo
Add squashfs collecting test

(and name this family of tests so its more obvious they belong together)
Simple test of romfs deployment
Add filedep deployment tests
Not providing tests for deployments/tools.py

...because I don't think we use it.

Annotate rrw.setup_tools with the same thought.
Ah, a test I forgot for collecting deployment
Minor tweakings
Erm, this one works
SquasFS deployment using common code from Collect
RomFS deployment now descended from Collect, too
Share what we can for filedep
Attempt to deal with Linux/BSD issues

i.e., BSD tar can extract from CPIO archives, but GNU tar cannot,
and GNU cpio has --no-absolute-pathnames, but BSD cpio does not.