Update Travis OS X build to use newest image. (#75)

Fixes #74.

.travis-scripts/install.sh

@@ -1,14 +1,6 @@
 #!/bin/bash
 
-if [[ $TRAVIS_OS_NAME == 'osx' ]]; then
-
-    # Install some custom requirements on OS X
-    # Get and install Java 8
-    wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u66-b17/jdk-8u66-macosx-x64.dmg
-    hdiutil mount jdk-8u66-macosx-x64.dmg
-    sudo installer -pkg /Volumes/JDK\ 8\ Update\ 66/JDK\ 8\ Update\ 66.pkg -target LocalSystem
-
-else
+if [[ $TRAVIS_OS_NAME != 'osx' ]]; then
     # Install custom requirements on Linux
     sudo add-apt-repository ppa:wpilib/toolchain -y
     sudo apt-get update -q

.travis.yml

@@ -6,6 +6,7 @@ matrix:
       dist: trusty
       sudo: required
     - os: osx
+      osx_image: xcode8
       env: WPILIB_FLAGS=-PskipArm
 
 addons: