Rename parameter 'tag' to 'vlan_tag' in l23network module

In puppet >3.0 word 'tag' is reserved, so it have to be
renamed.

Change-Id: Ie2b62d2b96ee9ca9d4ced15d038979561899e910
Closes-Bug: 1305600
Merge "Rename parameter 'tag' to 'vlan_tag' in l23network module"