[Charts] Fix Standalone charts now that Metrics authentication has changed

With the change in authentication to Metrics (now via Accounts) the standalone charts are now not properly authorized.
NOTE: This does not affect regular charting in any way.

The standalone way of having hawkular-charts automatically connect to a server and live update itself looks like this:

<hawkular-chart
chart-type="bar"
metric-id="server2.cpu.user"
metric-type="gauge"
metric-tenant-id="myTenant"
metric-url="http://127.0.0.1:8080/hawkular/metrics"
time-range-in-seconds="86400002"
refresh-interval-in-seconds="30" >
</hawkular-chart>

https://github.com/hawkular/hawkular-charts#stand-alone-live-updating-tag-example