Feature/test suite

Steve - please can you check my Python.
more readable to use `str.format`:

```
to_pass = '{osmpath} --read-pbf file="{latest_pbf}" --read-pbf file=....'.format(osmpath=foo, latest=pbf=bar)
```
And there are loads of other variations (you can just do `{}` instead of naming them, or `{0}` and then use positional-arguments) see: https://docs.python.org/2/library/stdtypes.html#str.format