rqt_marble: compile fix for Ubuntu 14.04

libmarble had some API change in Trusty.
https://projects.kde.org/projects/kde/kdeedu/marble/repository/revisions/603ebd97d3c373e26d2de950467060f480bf2e88

Note: I only tested this on trusty amd64.
Merge pull request #227 from forouher/fix/indigo/trusty

rqt_marble: compile fix for Ubuntu 14.04