Don't install metawrap via metawrap-mg

[yqy6611]

This is a suggestion.

metawrap-mg is totally outdated. Moreover, all of dependencies can actually work with python 3 without revising module scripts of metawrap.

Prepare a cleaner conda environment with python 3 and manually install those dependencies except for prokka and salmon can solve majority problems. For prokka and salmon, prepare separate environments for each of them and redirect the locations in scripts.

For some small auxiliary python 2 scripts we can prepare another python 2 environment and redirect python interpreter in those scripts. Of course it will be better if you can revise those scripts using python 3.