test/allocsim: ops scrapper arg parsing

test/allocsim: ops scrapper arg parsing

```
fedora :: pere/scrapper-replayer/build 130 » ./bin/replayer -h
All options:

Options:
  -h [ --help ]                 produce help message
  -i arg (=input.txt)           Input file (output of op_scraper.py)
  --ceph-conf arg (=ceph.conf)  Path to ceph conf
  --io-depth arg (=64)          I/O depth
  --parser-threads arg (=16)    Number of parser threads
  --worker-threads arg (=16)    Number of I/O worker threads
  --pool arg (=test_pool)       Pool to use for I/O
```

Signed-off-by: Pere Diaz Bou <pere-altea@hotmail.com>