Support for RunCommand

[junichi11]

I would like to use the following CLI tool:

• https://github.com/wp-cli/wp-cli
• http://wp-cli.org/

[junichi11]

UI

Options

• wp-cli script: Full path of wp-cli script e.g. /usr/bin/wp or /path/to/wp-cli.phar
• download locale: option for core download e.g. ja
• download version: option for core download e.g. 3.6.1

[junichi11]