Updated `.travis.yml'

Install from `share/unit/apt.conf' to prevent user-interactivity.

Install from `share/unit/rng-tools' to speed up RNG; this doesn't
currently work in the Travis CI environment for some reason.

Added coreutils to the packages list for `dd'.
Updated `share/examples/siterc.eg': Mac OS X

More useful aliases ready for use for Mac OS X users.