Implemented the services to list packages, their license and fetch license content.

Implemented the 3 license services. Tested using luna-send on the Ports Emulator

- listPackages

 luna-send -n 1 palm://org.webosports.service.licenses/listPackages '{}'

List directories in /usr/share/licenses

- listLicensesForPackage

luna-send -n 1 palm://org.webosports.service.licenses/listLicensesForPackage '{"package": "luna-service2"}'

List files in the  /usr/share/licenses/luna-service2

- getLicenseTextForPackage 

luna-send -n 1 palm://org.webosports.service.licenses/getLicenseTextForPackage '{"package": "luna-service2", "license": "Apache-2.0"}'

File content of /usr/share/licenses/"luna-service2/Apache-2.0