Install Ruby and Node with setup-devel.sh

[DanOpcode]

Let setup-server.sh install the compiled version of the frontend, while setup-devel.sh installs the frontend source repository including Ruby, Node, Gulp and Bower.

setup-server.sh works just as it did before, i.e. it installs the compiled version of the frontend. However, setup-devel.sh has been changed to install the regular source code repository of the frontend, including the tools necessary to compile it. This automates the frontend chapter of the setup instructions at http://taigaio.github.io/taiga-doc/dist/setup-development.html#_frontend_installation.