Implement loading a single plugin archive
Merge pull request #6 from gitblit/load_plugin

Implement loading a single plugin archive
a first version related to enable-disable plugin
forgot to commit these files
the content of disabled.txt was deleted accidentally when I run demo (that contains a sequence of code that enable programmaticaly a plugin)
added support for PluginManager.getExtensionClassNames(String pluginId) and simplify enable/disable plugin
use PluginState.DISABLE instead of PluginManger.isPluginDisabled()
Merge pull request #9 from decebals/enable-disable-plugin

Enable disable plugin
add listeners to plugin state changes