IsFree messages from properties files.
Merge branch 'develop' of git://github.com/dana-i2cat/opennaas into develop
Merge branch 'develop' of git://github.com/dana-i2cat/opennaas into develop
Improvement in IsFree feature.

-The isFree method only checks with other VCPE's.
-The isFree method allow for routers, e.g. two identicals interfaces in
differents routers is not an error.
-Internationalization in messages.
Rename msg names
Merge pull request #485 from jordi-puig/develop

Improvement in IsFree feature