update gitignore for python and .testrepository

ignore python byte-compiled files
and ignore the folder, '.testrepository', generated from tox command.

Change-Id: Ic0208ea2e7e1c046a3a730cbd83f676ce44ed2ae
Closes-Bug: #1491267

.gitignore

@@ -12,3 +12,11 @@
 # Files generated by tools/genenv
 openrc
 openstack.env
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# the files generated from tox command.
+.testrepository/