add vagrant logfile to .gitignore

Change-Id: I78dac96b5ea81d8c014916e0eeff043cdc78cbdb
diff --git a/.gitignore b/.gitignore
index 41be305..5518b83 100644
--- a/.gitignore
+++ b/.gitignore
@@ -68,3 +68,6 @@
 # Voltha CLI hostory files
 .voltha_cli_history
 **/.voltha_cli_history
+
+# Vagrant logfile
+*.log