Use valid category in library.properties
Use valid category in library.properties

The previous category value caused the warning:

WARNING: Category 'radio' in library Simple-WebRadio-Library-for-Arduino is not valid. Setting to 'Uncategorized'

List of valid category values:
https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#libraryproperties-file-format
DennisB66/Simple-WebRadio-Library-for-Arduino