OSX 10.11.6
node v6.9.1
npm v3.10.8
[sudo] npm uninstall -g angular-cli
[sudo] npm cache clean
[sudo] npm install -g node-gyp
[sudo] npm install -g node-pre-gyp
[sudo] npm install -g angular-cli
These 5 steps successfully installed angular-cli@1.0.0-beta.15