Implements the enable all plugins function.
remove unused variables
Merge remote-tracking branch 'tiagohillebrandt/master' into enable-all-plugins
add tests to `wp plugin activate --all` and `wp plugin deactivate --all`
Merge pull request #1467 from rodrigoprimo/enable-all-plugins

Add --all param to `wp plugin activate`
Merge remote-tracking branch 'upstream/master' into remove-unused-variables

Conflicts:
	php/commands/media.php
Merge pull request #1466 from rodrigoprimo/remove-unused-variables

Remove unused variables