added subset of signal11's hidapi, and simple makefile
added hidapi support, via PInvoke

* wrapped as a new HW interface, to replace SyncSerialPort (and the
IJsonReporter class, since HID reports will have custom data formats).
* fixed nullptr bug in BatteryController
* moved board controllers to separate file
* began writing HID-based board controllers
use $scope.signals_btn for all signal buttons, updated ng-class syntax