[imp] Change package structure

This changes the component structure to:
* Avoid tracking zip files with git
* Be able to use "Install from folder" directly choosing the local clone
* Be able to install directly the [zip file generated by github](https://github.com/ElevenPaths/latch-plugin-joomla/archive/master.zip)

It also adds creation date to all the extensions to avoid showing "Unknown" on extension manager:
![latch-unknown](https://f.cloud.github.com/assets/1119272/2096168/a732ab98-8efa-11e3-8f3a-d9a30d68b405.png)