Add gtk-sharp3 to ubuntu-precise; resolves travis-ci/apt-package-whitelist#1216
Add gtk-sharp3 to ubuntu-precise; resolves travis-ci/apt-package-whitelist#1216

Packages: gtk-sharp3 gtk-sharp3-examples gtk-sharp3-gapi libatk3.0-cil libcairo1.10-cil libgdk3.0-cil libgdk3.0-cil-dev libgio3.0-cil libgio3.0-cil-dev libglib3.0-cil libglib3.0-cil-dev libgtk-dotnet3.0-cil libgtk-dotnet3.0-cil-dev libgtk3.0-cil libgtk3.0-cil-dev libpango3.0-cil libmono-profiler-gui-thread-check monodoc-gtk3.0-manual

AlCutter/apt-package-whitelist,travis-ci/apt-package-whitelist,travis-ci/apt-package-whitelist,AlCutter/apt-package-whitelist