Testing for Acme Alien dists

These commits:

 1. Adds a pkg-config style `dontpanic.pc` file so that `libdontpanic` can be installed as a system lib and detected as such by `Alien::Base` and `Acme-Alien-DontPanic`
 2. Adds a .travis.yml for testing each push
 3. Adds a .gitignore
 4. numerous small fixes to get these things working

Note that ALIEN_FORCE=1 testing is broken because `Alien::Base` in CPAN will not install with that environment variable.  As soon as we get that fix into CPAN, these tests should start passing.