Merge branch 'devel' into dev/pluginLifecycleMgmt

Conflicts:
	src/octoprint/plugin/core.py

src/octoprint/plugin/core.py

@@ -121,9 +121,7 @@ class PluginInfo(object):
 		self._url = url
 		self._license = license
 
-		self._validate()
-
-	def _validate(self):
+	def validate(self):
 		# if the plugin still uses __plugin_implementations__, log a deprecation warning and put the first
 		# item into __plugin_implementation__
 		if hasattr(self.instance, self.__class__.attr_implementations):
@@ -552,6 +550,7 @@ class PluginManager(object):
 	def load_plugin(self, name, plugin):
 		try:
 			plugin.load()
+			plugin.validate()
 			self._activate_plugin(name, plugin)
 		except:
 			self.logger.exception("There was an error loading plugin %s" % name)