Speedup and improve isolation of acceptance tests

Each acceptance test used to generate a new RSA key, which added a lot of time
to acceptance test run time. RSA keys are actually used by just a tiny minority
of tests, so speed the things up by generating them only in the tests where it
matters.

Additionally, test suite pre-started several cf-serverd instances, also used by
a tiny minority of tests. Move startup/shutdown of those servers to the specific
tests itself. It also mean that actions of one test may not affect behaviour of
cf-serverd in another test.

Conflicts:
	tests/acceptance/16_cf-serverd/01_start/prepare_tests.srv
	tests/acceptance/testall
Unexport GetOwnerName
Move files_select.c to cf-agent
Unexport callback function
Remove unused functions
Unexport functions local to single module
Unexport VerifyOwner
Unexport VerifyFileChanges
Whitespace cleanup
Move CfCreateFile into cf-agent
Clean up files_operators.h file after mass move
Unexport DeviceBoundary

Conflicts:
	libpromises/prototypes3.h
Move SetSearchDevice to cf-agent

Conflicts:
	libpromises/prototypes3.h
Unexport SuspiciousFile
Add more comments to testall script
Move EmptyString to proper module