When aborting, flush log containing pre-mortem data

neo/admin/app.py

@@ -77,6 +77,7 @@ class Application(object):
         except Exception:
             logging.exception('Pre-mortem data:')
             self.log()
+            logging.flush()
             raise
 
     def _run(self):

neo/master/app.py

@@ -134,6 +134,7 @@ class Application(object):
         except Exception:
             logging.exception('Pre-mortem data:')
             self.log()
+            logging.flush()
             raise
 
     def _run(self):

neo/storage/app.py

@@ -167,6 +167,7 @@ class Application(object):
         except Exception:
             logging.exception('Pre-mortem data:')
             self.log()
+            logging.flush()
             raise
 
     def _run(self):