`organizations` models refactored.
Removed `organizations` migrations.
Removed `organization` field from abstract `projects` model.
`projects` app models refactored.
`organizations` app renamed.
`projects` app renamed.
`accounts` app renamed.
`contact` app renamed.
`projects` serializers and views cleaned up.
Deleted non-used mailing function.
Admin classes fixed.
`tasks` app renamed.
`bb_tasks` models reviewed.
Deleted `bb_accounts` migrations.
`bb_accounts` app code cleaning.
Merge pull request #224 from jose-lpa/refaktor

Refaktor initial cleaning-up