incompatibilities with conda-forge aipy

[jaguirre]

Using an aipy install from conda install -c conda-forge aipy and attempting to run ./mk_array_file.py -C hera127 fails to find aipy/aipy_src/_src/helm_fit.txt and aipy/aipy_src/_src/helm_pos.txt Not clear why `aipy is not installing these; they are present in https://github.com/HERA-Team/aipy