Make url redirect generic

To make ATDB being able to be deployed behind a proxy on different address
direct links to address have to be converted in local urls

To deploy on a different url also an environment variable should be set.
Such environment variable is called ATDB_PATH.
For instance if you want to deploy ATDB on https://sdc.astron.nl/asw/atdb
you have to define the environment as ATDB_PATH='/asw/'.