Add @recoverable decorator to retry operations upon connection error

Similar to the `@run` decorator, this decorator causes a wrapped
method to be retried in the case that the method throws an exception
which appears to be caused by a lost connection.

While the `@run` decorator is limited to wrapping methods with a
particular signature (including `query` and `bindings` params, the
`@recoverable` decorator is more generally applicable.

orator/connections/connection.py

@@ -18,6 +18,17 @@
 connection_logger = logging.getLogger("orator.connection")
 
 
+def recoverable(wrapped):
+    @wraps(wrapped)
+    def _recoverable(self, *args, **kwargs):
+        self._reconnect_if_missing_connection()
+        try:
+            result = wrapped(self, *args, **kwargs)
+        except Exception as e:
+            result = self._recover_if_caused_by_lost_connection(e, wrapped, *args, **kwargs)
+        return result
+    return _recoverable
+
 def run(wrapped):
     """
     Special decorator encapsulating query method.
@@ -356,6 +367,14 @@ def _try_again_if_caused_by_lost_connection(
 
         raise QueryException(query, bindings, e)
 
+    def _recover_if_caused_by_lost_connection(self, e, callback, *args, **kwargs):
+        if self._caused_by_lost_connection(e):
+            self.reconnect()
+
+            return callback(self, *args, **kwargs)
+
+        raise e
+
     def _caused_by_lost_connection(self, e):
         message = str(e).lower()