Add current company scope to SSE

* using UUID for pk in companies
* migrate exsiting tables to company_id:uuid
* simplify SSE messages
* add scope to SEE messages: current company
* fixed factories for company_id_fkey, implicitly create company
* create FK for projects -> builds -> jobs -> job_logs
* restore unique indexes after company uuid migration
Merge pull request #33 from vexor/uuid_primary_keys

Add current company scope to SSE