Alias forward command and easier flips

Adds aliased command 'forward' to 'front' to maintain consistency

Also adds alias to flip animations:

  - my.drone.frontFlip()
  - my.drone.backFlip()
  - my.drone.leftFlip()
  - my.drone.rightFlip()
Add wave command alias

Example:

    my.drone.wave()
Merge pull request #6 from hybridgroup/aliased-methods

Alias `forward` command and add easier flips