Fixed #1000: Defect - Plugin Version does not change on update

    [feedquote='i-MSCP Github (nuxwin)','https://github.com/i-MSCP/imscp/commit/b883d64dc3a4579e707c33eeb8c10f0e169bf96b']

    Code
    1. Fixed #1000: Defect - Plugin Version does not change on update
    2. Fixed: Plugin interface must always show the last plugin available version
    3. Fixed: Bulk action must not be a valid option (Plugin interface)
    4. Fixed: When a new plugin version is available, the plugin must be updated and not only enabled
    5. Updated: Plugin API to version 0.2.4

    [/feedquote]