Running snakemake does not recognize mamba

[AmitMY]

Following the instructions on the README, I get to the make dry-run step, and snakemake errors it does not know mamba.

To fix, I had to additionally

export PATH=$(conda info --base)/bin/:$PATH 

(where conda info --base is the same as CONDA_PATH in the Makefile)

[evgenyrp]

This issue happens because of a conflict with preinstalled conda. We should modify the Makefile so that it always uses our mamba installation for snakemake.