Update gf2.py, handle multiple pages
Merge pull request #31 from niczy/master

Add problemset_test.
Merge branch 'master' of https://github.com/gf2/gf2
Welcome page and responsive signup panel
Update gf2.py, parse pages from build.dart
Merge pull request #30 from charliezhang/master

Welcome page and responsive signup panel
Merge pull request #33 from niczy/master

Each section should have a type.
Init the request.