country should't be added when importing data

[bunop]

Is your feature request related to a problem? Please describe.
Uploading data let people to add countries during breeds creation. This could lead to insert mispelled countries or terms that can't be annotated using the chosen ontologies.

Describe the solution you'd like
No new countries can be generated while importing data

Describe alternatives you've considered
Things could remain as they are, however could be difficult to manage ontologies and data manually

Additional context
This aspect is described also in #50. Ideally those things need to be addressed

• prevent to create new countries when creating breeds
• assert that countries are in database before data load (like check_species)