Expose scan settings in centralScanning

[PietroGranati]

After a bit of research and thanks to @m1ga I found out that in ScanManagerAPI21Onwards.java there is a hardcoded setting that can be useful:
scanBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER);
In fact this prevent the module sto scan for beacon at maximum effort so I modified it in:
scanBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY);
And now it's much better, maybe you can expose the settings.

Ref:
https://developer.android.com/reference/android/bluetooth/le/ScanSettings#SCAN_MODE_LOW_LATENCY

[m1ga]

Thanks for the note! I'll see if I can implement that soon

[m1ga]

untested but I added a scanMode property to initCentralManager. There you can pass in one of the constants.
Check the #294 PR