support alembic 0.7.0
remove pdb
support alembic 0.7.0
Merge pull request #84 from item4/upgrade/alembic

Upgrade: support alembic 0.7.0
Remove one web and crawler instances
Update requirements to install alembic 0.7.0
Merge pull request #85 from tkiapril/alembic-7

Update requirements to install alembic 0.7.0
Merge pull request #83 from tkiapril/reduce-server

Remove one web and crawler instances