(QENG-912) Beaker 1.14 breaks PE Puppet Acceptance

- was too conservative in removing non utf-8 compliant characters -
  ended up removing compliant characters along with undef/invalid
  character codes
- tested locally and it preserved messages like:
/etc/puppet/modules
├── jimmy-appleseed (v1.1.0)
├── jimmy-crakorn (v0.4.0)
└── jimmy-thelock (v1.0.0)
- correctly removed actual undef/invalid characters so that string
  methods can be run (ie, split, gsub)