VOL-1460 Ignore voltha-protos working directory

Change-Id: I3c55a6c88e1d80ebc6c5e9b527569779efc85bea
diff --git a/.gitignore b/.gitignore
index 04760cb..5fd0857 100644
--- a/.gitignore
+++ b/.gitignore
@@ -64,4 +64,5 @@
 
 # Development versions of locally built libraries
 python/pyvoltha
+python/voltha-protos