Implementation of a plugin parser #14
Adds a plugin manager to list the installed plugins
adds tests for pluginmanager
adds a method to put the list of plugins into a cache, and retrieve the values from the cache.
adds a function to calculate plugins new versions
adds test
adds a function to get uninstalled plugins
sets plugin management as a plugin
Isolates the plugin in its own file
Begin the implementation of the panel config for the plugin management
Evolution of the plugins panel
Adds toggle button to DownloadPluginPanel
Fixes issues with enabling  / disabling plugins
Adds gradle files
fixes multiple bugs
Fixes a bug disabling a plugin
Adds messages when enabling / disabling plugins
Adds a methods to refresh the cache in a background thread
adds an icon to show that a plugin has an update
Renames Plugin to ExtensionPoint