feat/PHAL_validator (#42)

Co-authored-by: jarbasai <jarbasai@mailfence.com>

ovos_plugin_manager/templates/phal.py

@@ -3,13 +3,23 @@
 from ovos_utils.messagebus import get_mycroft_bus
 
 
+class PHALValidator:
+    @staticmethod
+    def validate(config=None):
+        """ this method is called before loading the plugin.
+        If it returns False the plugin is not loaded.
+        This allows a plugin to run platform checks"""
+        return config.get("enabled", True)
+
+
 class PHALPlugin:
     """
     This base class is intended to be used to interface with the hardware
     that is running Mycroft.  It exposes all possible commands which
     are expected be sent to a PHAL plugin.
     All of the handlers are optional and for convenience only
     """
+    validator = PHALValidator
 
     def __init__(self, bus=None, name=""):
         self._mouth_events = False