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

This is a (potentially doomed) initial attempt at automated conda packaging of openmm-dev.
This exclusion exists because @peastman thinks OpenCL on travis-ci is broken.

@pgrinaway and I think that travis-ci is using the AMD OpenCL implementation here, which I believe uses some different kernels than OpenCL on NVIDIA.  We're worried there may actually be a bug, and we should actually be running the OpenCL tests here on travis-ci.  

When was the last time anyone tested OpenMM on AMD OpenCL?