Updated `.travis.yml': travis-ci matrix, rng, apt

Split out the various modules into independent travis-ci matrix items;
this way it is easy to see the health of each module without having to
read the actual output of the unit test.

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'.
New `share/unit/travis': Travis CI multiplexer

This script uses env variables set via `.travis.yml' to direct various
unit test execution paths, and has made unit-testing more efficient.
Fixed `module/hgd': touch `hgd.conf' if need be