Merge pull request #237 from jose-lpa/refaktor

Fixed testing settings
updated test model references, added demo tasks in unittests that work
Merge pull request #238 from jose-lpa/refaktor

Fixed testing settings to use PostgreSQL.
Merge pull request #239 from aethemba/refaktor

updated test model references, added demo tasks in unittests that work
Merge pull request #240 from jose-lpa/refaktor

Initial migrations for abstract applications.
Merge pull request #246 from jose-lpa/refaktor

`bb_tasks` app fixes
Merge pull request #249 from jose-lpa/refaktor

Some more fixes to the `bb_tasks` app.
Merge pull request #252 from jose-lpa/refaktor

Fixed `bb_tasks` serializers.
Attempting to fix Travis tests execution...
Fixed factory model for user accounts.
Fixed admin models for `bb_organizations`.
Fixed admin models in `bb_tasks`.
Fixed admin models in `news`.