Fix imports; fixes unittests

Conflicts:
	src/ggrc/converters/base_row.py
Merge pull request #553 from reciprocity/feature/fix-import-imports

Fix imports; fixes unittests
Add return_to query string to sections.
Add fallback url in case return_to param is missing.
Merge remote-tracking branch 'origin/feature/importRedirectError' into feature/importRedirectError

Conflicts:
	src/ggrc/views/__init__.py
Resolve merge conflict.