Sometimes some hosts should be configured with an interface without any
IP address set (e.g. bridged interface) and to achieve that this change
adds the new attribute 'no_ip' for the network configuration. Also the
change contain a test for this.

Change-Id: I2c9dfeca7f0d37a96f9cbd9df51d94098cf07258
Signed-off-by: Maksim Malchuk <maksim.malchuk@gmail.com>