Territory should dictate the SRS

[RicardCots]

Is your feature request related to a problem? Please describe.
When creating a new SITMUN application, an SRS must be specified. The same application could be useful for territories with different main SRS (e.g. a generic viewer for Navarra EPSG:25830 and for Menorca EPSG:25831). As it is configured now, a different application has to be defined for each territory with a different BSS even if the application has the same features.

Describe the solution you'd like
A new field in the territory form to specify the EPSG. This would also give more consistency to the centre and bounding box co-ordinates fields which are now not linked to any reference system.

This field should come from what is defined for that territory

[fjlopez]

Create backend support.

[fjlopez]

@lucenasj added field srs to the territory