Added simple captcha data and tag base classes and indexes.
Added simple captcha data and tag base classes and indexes.

Removed duplicated field on message base.

Performed some pep8 gromming.

Refs: #6

candango/diasporapy,piraz/diasporapy,piraz/podship,piraz/diasporapy,candango/diasporapy,piraz/podship,piraz/diasporapy,candango/diasporapy,piraz/podship