Recipe updated for OpenMM 6.2 release

Also added some manual file moves to put the examples in a better place (#58).  This is a temporary hack for 6.2, we may want to improve it for 6.3.

Files (Linux) are currently on my personal binstar.  I can upload them to `omnia` once we've done a bit of testing.

```
conda install -c https://conda.binstar.org/kyleabeauchamp openmm
```