Automated conda packaging of openmm-dev [ready to merge]

This is a (potentially doomed) initial attempt at automated conda packaging of openmm-dev.
Which lines specifically?  Do you mean
```

+if [[ "$python" != "2.7" ]]; then
 +    echo "No deploy on PYTHON_VERSION=${python}"; exit 0
 +fi
```
We can certainly delete it.  This was simply copied from what @kyleabeauchamp had in `repex` and `yank`.