Inititial work on Linux-IO backstore RA script

Can set up a basic target device (tested with iblock so far), tear it down, and
monitor it. Passes the ocf-tester test suite, just. This is by **no means**
complete yet.

Sample command-line for ocf-tester:

```
ocf-tester -v -n p_backstore_test1 \
	-o hba_type=iblock \
	-o name=test1 \
	-o device=/dev/vg_chris/test1 \
	-o unit_serial=1e3e6f8a-b7ea-46cf-a8eb-294c52c4a015 \
	-o attrib='is_nonrot=0 emulate_model_alias=1' \
	/home/crb/Projects/ocf-lio/backstore
```

Signed-off-by: Chris Boot <crb@tiger-computing.co.uk>