LD_LIBRARY_PATH problems

We try to automatically install WASP for those who don't have it, but
1. The conda envs must have LD_LIBRARY_PATH set inside them. Otherwise, snp2h5 won't work
2. Also, if the user is manually installing dependencies, you shouldn't assume that their HDF5 libraries are in the conda directory (or indeed, that conda even exists on their machine). Instead, specify this as an optional config option.