Add an command line option to define a single matcher to use

[gaurav]

This is surprisingly easy to do: we need an "-m" type command in the format "-m key=value". You can specify multiple options, but this allows you to quickly run GNA queries ("-m gna_id=1,2,3,4"), GBIF queries ("-m gbif_id=123456789-1234-....") or reconciliation services ("-m recon_url=http://reconcile....").