Update travis

Author: nixel2007

.travis.yml

@@ -14,8 +14,11 @@ before_install:
       sh -e /etc/init.d/xvfb start;
       sleep 3;
     fi
-  - wget -O os.deb http://oscript.io/downloads/night-build/deb
+  - sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
+  - echo "deb http://download.mono-project.com/repo/ubuntu trusty main" | sudo tee /etc/apt/sources.list.d/mono-official.list
+  - sudo apt-get update
   - sudo apt-get install mono-complete mono-devel
+  - wget -O os.deb http://oscript.io/downloads/night-build/deb
   - sudo dpkg -i os.deb; sudo apt install -f
   - sudo oscript /usr/share/oscript/lib/opm/src/opm.os install opm
   - sudo oscript /usr/share/oscript/lib/opm/src/opm.os install logos