No DB

*** DO NOT MERGE ***

Fully stateless portal - DB stripped out.

Things that were removed:
 * DB - No more DB whatsoever, no more hibernate, no GORM
   * This entails also no AODAAC
 * ~20K lines of code

How filters work - they are taken from `filters/LAYER_NAME.xml`.

How to get the filters (transform from JSON to XML and store locally):
```
./get_filters.rb -u https://catalogue-123.aodn.org.au/geonetwork -g http://geoserver-123.aodn.org.au/geoserver/wms -p https://imos.aodn.org.au/imos123 -d filters
```

Test and enjoy!
`allowedHosts` could still get initialised more than once. To protect form this we need to check `allowedHosts` again from within the synchronised block.