MiniMaven: add forgotten 'else'

Without this 'else', the -D<key>=<value> options stop working all of a
sudden.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
MiniMaven: point out unknown options

Rather letting the user guess which of the command-line options could
not be understood, let's try to be nice and report the unknown option.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
MiniMaven: Bio-Formats and SCIFIO also have diverging jai_imageio

Let's handle them the same as the scifio artifacts: put Bio-Formats'
version into bio-formats/.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'mini-maven-fixes'

Assorted fixes for MiniMaven... one very crucial to make Fiji's Build.sh
work again: MiniMaven stopped handling -D correctly by mistake.

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