Log Message:
Changes 0.27:
- Hotfix for `perlbrew install` command

Changes 0.26:
- Fix GH 119
- Fix t/08.exit_status.t for cpantesters
- Fix several bugs in `exec` command
- Implement GH 103 - install -v shows build.log
- Add -Dusedevel when installing blead perl

Changes 0.25:
- suggest when user types wrong commands.
- Improvements about self-upgrade.
- exit with non-zero status code when there's some sort of error.
- Added verification of existing alias before attempting unalias.
- Fix `install-cpanm` for due to a recenet github cert update.