Respect rpmbuild's argument ordering for #309

rpmbuild is weird (on OSX at least) and requires target to come before
the --defines.
Merge pull request #315 from mashion/target-os-fix

Respect rpmbuild's argument ordering for #309
* Fix #319 Add Debian Predepends.
Merge pull request #320 from r4um/fix_predepends

Fix #319 Add Debian Predepends.
- add coverage for the default os value
- only set 'target' if the --rpm-os flag is set
  (Fixes #321, #314, #309, #vagrant/1277)
- fix comment
- update changes
- version bump
- @rpmtag should be @rpmtags
- rpm 'release' is a string, I guess?
Bandaid fix for Issue #316. Without digging too deep into commmit a88cca4