Fix null pointer exception processing result of "getTotalBandwidthSavedInMB"

This is to resolve Issue #10.

In "initInfoPanel", there is a call to "getTotalBandwidthSavedInMB". This function can return null, for example if there is an exception parsing a preference to a float. However, the invoking code always assumed a non-null result, and was calling ".toFixed(2)" on the result. This has the upshot of preventing the video from actually being displayed.