improve -of13 switching in distributions/base (BUG 802)

- if of13 is not involved, remove openflowplugin config
- if of13 is involved, create symbolic link to openflowplugin config

Change-Id: I8de221a428a66452aeedbae35352b41932b6ab74
Signed-off-by: Michal Rehak <mirehak@cisco.com>