Enable to select specific network service type

Network service type is selected as 'network' statically.
This will select the service_type from environment variables or CLI options.
The option works like the service type option in the novaclient.

Implements blueprint specify-service-type
Change-Id: If21bd2b5cb35da5bcabca79aa0567870331a3a6f
Use six.moves.urllib.parse to replace urlparse

Import six.moves.urllib.parse as urlparse for python3 compatible.

Change-Id: Icc6dc92c4d4016b8a4f1118220a51415d2b5feb0
Closes-Bug:#1279611
Merge "Use six.moves.urllib.parse to replace urlparse"
Merge "Enable to select specific network service type"