Update to Ext JS 5 (fixes wilk/Ext.ux.data.proxy.WebSocket#12)

This version does work on Ext JS 5.

Known issue: Chart in Ext JS 5 does not render correctly after updates in the store.
Known issue: Removed `rownumberer` from the demo grid because of bug EXTJS-13759 (fixed in Ext JS 5.0.1).