Add download/db-construction size/time estimation module

[kbshimmyo]

There's a TODO comment to indicate where this gets plugged in.

[arvkevi]

@halekpetigo does fbc0226 resolve this issue?

[halekpetigo]

Yes, if we include the taxosize python script in mapper_wrapper.sh at line 127 <# TODO: this is where we should plug in the download size/time estimator>, that should address this issue. The Python script provides the size of the genome. The time to download depends on the network of the user hence difficult to estimate. Maybe we can provide a rough order of magnitude if we want to include the time.