DRYing FileUtils#appendContents

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix URL encoding of listContents() for jar: URLs

Spaces. The final frontiers. And they weren't handled correctly.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Verify that even non-ASCII is handled by FileUtils#listContents

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'list-contents'

This fixes the problems on the SciJava-common side that ImageJ2's lookup
tables stored in ij-data.jar in a subdirectory containing a space in its
name were not discovered properly.

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