Build.sh: exit with an error if MiniMaven failed

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Build.sh: make sure that scijava-common is installed

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Switch to a -SNAPSHOT version of MiniMaven temporarily

Sonatype has problems, so our deployment of MiniMaven 2.1.1 timed out :-(

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Switch MiniMaven back to release version

It took a while, and this developer interrupted the nexus-stagin maven
plugin *just* so it would not time out, and released manually. But
we do have a working MiniMaven 2.1.1 now.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>