Use instance specific Galaxies

[cvandeplas]

Today the MISP Galaxies used are those from the MISP-galaxies public project.
A copy of the github repository is downloaded and the local data is used.
This was done because of limited support of the Galaxies by MISP webui. (for example: relations are not supported)

Once MISP supports the galaxies fully (see MISP/MISP#3801), MISP-maltego should use the REST API to query the galaxies, as a MISP instance might have private non-public galaxies.