Resizable split pane (#190)

* Integrating with react-split-pane

* block event while resizing panels

* bring scrollsync back

* fixed footer position

package.json

@@ -135,6 +135,7 @@
     "react-sidebar": "^2.2.1",
     "react-simple-dnd": "^0.1.2",
     "react-sortable": "^1.2.0",
+    "react-split-pane": "^0.1.57",
     "react-toolbox": "^1.2.1",
     "react-topbar-progress-indicator": "^1.0.0",
     "react-waypoint": "^3.1.3",