Re-do java-8 handling, add unattended switch to toplevel Makefile

Change-Id: Ifaea353be5b42bb6edbcfa0506d02b721c00e392
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/build-root/vagrant/build.sh b/build-root/vagrant/build.sh
index 45a7eb4..aaaa62f 100755
--- a/build-root/vagrant/build.sh
+++ b/build-root/vagrant/build.sh
@@ -34,7 +34,7 @@
 
 # Install dependencies
 cd $VPP_DIR
-make install-dep
+make UNATTENDED=yes install-dep
 
 # Really really clean things up so we can be sure
 # that the build works even when switching distros