$ sudo snappy install ros-example_1.0_amd64.snap --allow-unauthenticated
Installing ros-example_1.0_amd64.snap
2016/01/12 14:42:14.926250 verify.go:85: Signature check failed, but installing anyway as requested
2016/01/12 14:42:37.012240 snap_local.go:336: Can not create "/snaps/ros-example.sideload/IKFUdCYASSOJ": mkdir /snaps: read-only file system
ros-example_1.0_amd64.snap failed to install: mkdir /snaps: read-only file system