Make the constraints for template dynamic

[josenavas]

Currently they're hardcoded. A better solution might be to make use of python configuration files so this is completely parametrized and dynamic at run time. If we change our requirements and/or EBI does, it will be very simple to modify it, rather than having to do a refactor of the code...

[antgonza]

I think we can close this one. @josenavas?

[josenavas]

We may want to leave it open and discuss a bit in the future. Right now, if you want to change the requirements, you actually have to change the code in constants.py. The idea was to actually source those values from a config file.

What do you think? It is worth or the system is actually so tied up to those values that is ok to leave in code?