updated Desktop project to be compatible with Android studio. The project can now be build and run from android studio, and should pass the travis ci build.
As part of that process, I cleaned up android dependencies in the 'Core' and 'Mavlink' project.
 The 'Core', and 'Mavlink' projects, are now pure java projects, which is fine since the 'Android' project can still use them as dependencies.
updated generated classes output build path
updated path to the drone icon.
Merge pull request #963 from ne0fhyk/desktop

Desktop Android studio support