Fix uploading binary wheel.

The script now takes two prompt for user name and password. One single
input redirection no longer works.

python/release/wheel/protobuf_optimized_pip.sh

diff --git a/python/release/wheel/protobuf_optimized_pip.sh b/python/release/wheel/protobuf_optimized_pip.sh
index 064d1d2..98306f4 100755
--- a/python/release/wheel/protobuf_optimized_pip.sh
+++ b/python/release/wheel/protobuf_optimized_pip.sh
@@ -6,7 +6,7 @@
 
 # Print usage and fail.
 function usage() {
-  echo "Usage: protobuf_optimized_pip.sh PROTOBUF_VERSION PYPI_USERNAME PYPI_PASSWORD" >&2
+  echo "Usage: protobuf_optimized_pip.sh PROTOBUF_VERSION" >&2
   exit 1   # Causes caller to exit because we use -e.
 }
 
@@ -25,7 +25,7 @@
   exit 1
 fi
 
-if [ $# -lt 3 ]; then
+if [ $# -lt 1 ]; then
   usage
   exit 1
 fi
@@ -63,7 +63,4 @@
   build_wheel $PYTHON_VERSION
 done
 
-/opt/python/cp27-cp27mu/bin/twine upload wheelhouse/* <<!
-$PYPI_USERNAME
-$PYPI_PASSWORD
-!
+/opt/python/cp27-cp27mu/bin/twine upload wheelhouse/*