v0.0991

      [INCOMPATIBLE CHANGES]

      - The --skip-missing-prerequisites option has been replaced with two
      separate options: 1)  --skip-missing-prerequisite (without the final "s")
      requires you to specify the name of the packages you want to skip.  This
      option can be repeated.  2) --skip-all-missing-prerequisites does not
      require an argument and causes Pinto to skip all missing prereqs.  These
      options can be abbreviated as -k and -K respectively.