Release v2.0-d4012a4

[costero-e]

This is the new release for beacon PI, which adds:

• Models plug in. Beacon PI now accepts different beacon flavours, based on different model specifications. Kicking off with two models: ga4gh beacon v2 default model and EUCAIM.
• Conf now is not affected by further releases. Use your conf and keep it forever.
• Cross queries between collections and non collections now are ready to be performed at full power.
• Schema request now working: feel free to request any schema you'd like for beacon to return.
• Validation on the fly per framework and model(s).
• Configuration of the entities of each entry type now done by .yml files.
• Restart of the app when conf files or generic conf is modified (no need to rebuild).
• Other bug fixes
• Unit tests expanded, with a total of 313 now.