fix .flowgraph urlpattern so that the dot is escaped and the URL inclues the app_namespace if it's defined. This yields URLs like 'purchase.flowgraph' which is useful if you use django-flows extensively, like we do.
add FlowHandlerBase so we can display all flows in one big flowgraph PNG
merge feature/add-fullflowgraph-view
merge feature/fix-flowgraph-regex