Build packages on Travis

[brodock]

This pull request is a followup of #14 and will build packages on travis and upload it to github tagged releases.

See https://github.com/brodock/apt-select/releases/tag/0.1.0 as an example of automatically generated package.

All you have to do is tag your commit with the same version number your package have.

For further versions, you have to edit deb-package.rb version and tag the appropriate commit with the same version found there.

[jblakeman]

@brodock Thanks for this pull request. Packaging and distribution are things I've been wanting to address.

Given that apt-select is an Ubuntu specific program, I've decided to start working on making Launchpad the distribution platform.

In the meantime, I recommend that anyone looking for a .deb package use this fork. fpm and fpm-cookery seem like very useful tools.