v0.3.0

Major Enhancements

• Officially drop 1.8.7 support (#14)
• Allow Commands to set their own versions (#17)
• Show subcommands, options and usage in help and attach to all commands (#18)
• Add -t, --trace to allow full exception backtrace to print, otherwise print
  just the error message (#19)

Minor Enhancements

• Logging state is maintained throughout process (#12)
• Tidy up Command#logger output (#21)

Development Fixes

• Added specs for Program (#13)