Cluster Management

Our awesome new cluster management page.

- [x] Add node.
- [x] Implement ring not ready state.
- [x] Implement legacy state.
- [x] Poll for updates to the plan.
- [x] API for updating the plan.
- [x] Wire up clear plan button to delete action.
- [x] Wire up commit plan action.
- [x] No plan state
- [x] Loading indicators
- [x] Error state indicators
- [x] Verify CSRF token protection works
- [x] Figure out bug when there is no plan and it doesn't update
- [x] When removing one node from two, it shows claim incorrectly.
- [x] Come up with custom error states (last, nice to have)
- [x] Ensure post works with no body.
- [x] Verify button is clicked.
- [x] State for no replacement nodes
- [x] Front page fixed width font
- [x] spans should be labels in action and for comit
- [x] Colorized arrows
- [x] Close notifications
- [x] Add warning for changes to node hosting riak control.
- [x] Disable actions on nodes after they've been staged; re-enable if plan is cleared