Fixes #733

Use fixed theme repo
fix some small documentation errors
Added app reference to SQLAlchemy DB instance. Fixes #736, fixes #737
Refactor: added setup_db function
Merge pull request #739 from PyBossa/issues-736-737-export-error

closes #736 closes #737
use merged master pybossa theme submodule now. Fixes #735
Merge branch 'issue-733-500-page-rendering'
Merge branch 'master' into issue-683-uploader

Conflicts:
	pybossa/themes/default