Cosmetics
Include local::lib in repository

This makes Mist 100% self-contained
Updated mist env

This ensures that mist installs cleanly on all perls from 5.10 up to 5.18
Use realpath() to find extlib
Command abstracts
Lots of mpan-install updates

- Consistent handling of @ARGV
- Added --all-available-versions option to mpan-install
- changed --perl to --perlbrew so it does not clash with cpanm's option
- Now supports installing of single modules via ./mpan-install
- perlbrew script once again supports --perlbrew=system to
  disable use of perlbrew altogether