[orca-list] Update Pluginsystem for Orca

[chrys <chrys linux-a11y org>]

Howdy List,

i added some more stuff to the plugin_system branch:

* The PluginActive State is now loaded from orcas settings file. The 
following plugins are active by default:

    - HelloOrca
    - ByeOrca
    - Time
    - Date
    - MouseReview
    - Clipboard

* Orca does now save the active states of plugins now in its settings file.

* The plugin manager asks for confirmation when uninstall an plugin to 
avoid remove it by ooops.

* The Readme refers now to libpeas

* i added an roadmap to plugin_system branch

https://raw.githubusercontent.com/chrys87/orca-plugin/plugin_system/TODO

Testers are welcome :).

please backup your settings folder:

 ~/.local/share/orca/

to get sure you can recover if somethings bad happens.

cheers chrys