Fix several naming/scope errors.

 - "quickstart.py:292: No global (EEXIST) found"
 - "basic_client.py:194: No global (option_parser) found"
 - "rsa_key.py:108: No global (EnvelopeError) found"
 - "rsa_key.py:108: No global (KeygenError) found"
 - "util.py:56: No global (temp_dir) found"