Implement string interpolation.
Make more similar to builtin format command.
Add tests for join.
Use short distro name, if the linux distro has no codename
Add support for pacman
Prune unncessary function from global bootstrap.
Only use apt when apt-get is available.

Avoid assuming all Linux machines are Ubuntu/Debian flavours.
First cut at installs_with_pacman predicates.
Merge branch 'fhahn-arch-linux'

* fhahn-arch-linux:
  First cut at installs_with_pacman predicates.
  Only use apt when apt-get is available.
  Add support for pacman
  Use short distro name, if the linux distro has no codename
Include pacman in managed_pkg/1.
Fix typos in referring to pacman.
Fix the pacman update once mechanism.