Ensure that all args with spaces in them remain quoted when used with command_wrapper.py.

Before this change, a command like : 

echo "1" "2" "3 4"

would be executed as :

echo 1 2 3 4

After this change, it will be executed as:

echo 1 2 "3 4"

Review URL: http://codereview.chromium.org/8597020

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/command_wrapper/bin@111020 0039d316-1c4b-4281-b951-d872f2087c98