Remove gettext-commons-maven-repository

The Transifex Jenkins build was failing because Jenkins couldn't find
the maven-gettext-plugin. Now we compile it on Jenkins and deploy it to
repo.orbisgis.org (as well as gettext-commons), so we don't need this
repository anymore.
Merge pull request #541 from agouge/mvn_gettext_plugin

Remove gettext-commons-maven-repository

The Transifex Jenkins build was failing because Jenkins couldn't find
the maven-gettext-plugin. Now we compile it on Jenkins and deploy it to
repo.orbisgis.org (as well as gettext-commons), so we don't need this
repository anymore.