Fix bug in pkg.is_installed with package names that are part of other package names.
Use human readable pkgin subcommands instead of abbreviations.
Merge remote-tracking branch 'origin/feature/fix_pkg_is_installed' into bleeding_edge

* origin/feature/fix_pkg_is_installed:
  Use human readable pkgin subcommands instead of abbreviations.
  Fix bug in pkg.is_installed with package names that are part of other package names.