Correctly identify PEM files generated from PKCS12 files in oauth2client.

Reviewed in https://codereview.appspot.com/19380043/.

Fixes issue #249.
diff --git a/tests/data/create-private-keys.sh b/tests/data/create-private-keys.sh
old mode 100644
new mode 100755
index b21cbdb..aaec580
--- a/tests/data/create-private-keys.sh
+++ b/tests/data/create-private-keys.sh
@@ -7,3 +7,7 @@
 openssl pkcs12 -export -out privatekey.p12 \
   -inkey privatekey.pem -in publickey.pem \
   -name "key" -passout pass:notasecret
+
+openssl pkcs12 -in privatekey.p12 \
+  -nodes -nocerts -passout pass:notasecret \
+  -passin pass:notasecret > pem_from_pkcs12.pem
\ No newline at end of file