Added Elphel ImgageJ-repo to .gitignore

We don't need to track [their repo](http://elphel.git.sourceforge.net/git/gitweb.cgi?p=elphel/ImageJ-Elphel;a=tree) here...
Add Java

Add Java and JDK to the setup of the Raspberry Pi, so we can compile ImageJ Plugins (from Elphel)
MTF/OTF-Measurements

Added some notes to perform the measurement of *m*odulation or *o*ptical transfer function