[plasticrake]

This change allows you to call start() on a source after calling end().

Currently the following code will not work:

a2dp_source.start();
delay(1000);
a2dp_source.end();
delay(1000);
a2dp_source.start();  // Does not start and logs error `initialize bluedroid failed` 

As the existing variable is_bluedroid_initialized is set to false when end() is called even though it is still initialized.

[pschatzmann]

Thanks for your contribution!