Remove old info['n_answers']
Don't use old style n_answers in tests
Update default theme
Add alembic migration script for n_answers
Merge branch 'master' into issue-874-n_answers

* master:
  Fix
  Don't modify the n_answers attribute when calling pct_status

Conflicts:
	pybossa/model/task.py
Merge pull request #875 from PyBossa/issue-874-n_answers

Issue 874 n answers