[travis] Cache Maven local repo for faster builds
[travis] Cache Maven local repo for faster builds

And cleaner build logs :)

fedora-java/xmvn,mizdebsk/xmvn,mizdebsk/xmvn,fedora-java/xmvn,fedora-java/xmvn,mizdebsk/xmvn,mizdebsk/xmvn