Add option for running offline

[jfy133]

Some clusters may have computing nodes that are offline.

@maxibor says that currently adrsm uses:

(Using the JGI API to convert TAXID to species name)

Therefore errors such as

requests.exceptions.ConnectionError: HTTPConnectionPool(host='taxonomy.jgi-psf.org', port=80): Max retries exceeded with url: /tax/pt_name/GCA_013267415 (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x2b5d41b17668>: Failed to establish a new connection: [Errno 110] Connection timed out',))

can happen, if no external internet access is avaliable.

An option to run the tool offline (e.g. using ete3 toolkit) would might be helpful for the above use-case.