Bug fixes, refactoring and "new" tests for the build manager

- Fixes various bugs introduced in the most recent build system commit
- Refactors state management in the build manager to be cleaner and more contained
- Adds back in the mock-based tests, fixed to not use threads and adjusted for the refactoring
- Adds some more simplified unit tests around non-etch related flows

buildman/manager/executor.py

@@ -48,6 +48,11 @@ class BuilderExecutor(object):
     default_websocket_scheme = 'wss' if app.config['PREFERRED_URL_SCHEME'] == 'https' else 'ws'
     self.websocket_scheme = executor_config.get("WEBSOCKET_SCHEME", default_websocket_scheme)
 
+  @property
+  def name(self):
+    """ Name returns the unique name for this executor. """
+    return self.executor_config.get('NAME') or self.__class__.__name__
+
   @coroutine
   def start_builder(self, realm, token, build_uuid):
     """ Create a builder with the specified config. Returns a unique id which can be used to manage