Gitified version of the official Loco Wordpress plugin:
http://wordpress.org/plugins/loco-translate/

Please report issues in the Wordpress plugin directory support forum:
http://wordpress.org/support/plugin/loco-translate

Note that the actual name of the plugin is "loco-translate" not "wp-loco". It's renamed on Github to differentiate it as a Wordpress plugin.

Add the plugin to your Wordpress project via Git as follows:

$ git submodule add git@github.com:loco/wp-loco.git wp-content/plugins/loco-translate

If you want to use a stable release listed in the Wordpress plugin directory, you can checkout by tag, e.g:

$ cd wp-content/plugins/loco-translate 
$ git fetch origin --tags
$ git checkout tags/x.y.z

Be sure to check the latest version by typing git tag and replacing x.y.z in above example.