Created statements subpage and button to generate it

- Create subpages for statements
- Added statement to csv feature
- Added Create statement button on all-venture sudpage
Revrite converting to unicode
Add comments
fix flake8
Show Download CSV button in statements only when any statement is choose

- Show Download CSV button in statements only when any statement is choose
fix notic
Fix migrations
Merge pull request #161 from kula1922/feature/monthly-statemant

Feature/monthly statemant