fix broken windows path (#247)
fix broken windows path (#247)

Current version seems to handle windows paths improperly

``` sh
docker: Error response from daemon: Mount denied:
The source path "C\\:/Users/Paul/Development/solidangle/match-api/app/.serverless/requirements\\:/var/task\\"
is not a valid Windows path.
See 'docker run --help'.
```

Calling `dockerPathForWin` on `bindPath` creation resolves issue.


UnitedIncome/serverless-python-requirements,UnitedIncome/serverless-python-requirements