GH #268 - Read version from one place only.
Merge branch 'dsuch-f-gh268-one-version-info'
GH #184 - Updated migration's comment.
GH #229 - Migration rename.
GH #184 - Migration rename.
GH #236 - Added Alembic migration.
Merge branch 'dsuch-t-gh236-postgres-add-migration'
Merge branch 'master' into dsuch-f-gh265-cassandra-client