Add new class stubs
Move the v2 tests under the v2 tree
Add a README for the v2 unittests
Remove extraneous __init__ to fix v2 unittests
Somehow, git mv only rm'd test/v2 and didn't add v2/test
Remove temp file
Fix missing import
Fix relative imports
Starting to stub out some classes.
Stub out Inventory class - we're going to draw heavily on the existing
inventory for implementation
Add python3 compat boilerplate to executor
Add python3-compat boiler to all core files
Give all v2 tests the python3 compat boilerplate
Remove inherit from object as it's no longer needed to determine new-style classes
Updating unittests for v2 stuff
Preserve backup files

This commit introduce two distinct changes:

- an existing backup file is never overwritten;
- the backup extension is the same for all backups in a given run.

Without this commit if a file is modified multiple times in the same
play only the last edit can be rolled back.

Signed-off-by: Walter Franzini <walter.franzini@gmail.com>