Update README.md
add note about 4Gb limit of wrapper.java.maxmemory property
update to siesta 1.5
update to 1.5.2 sisu-bundle-launcher
use litmus 1.7
use problem reporter 1.5.4
Merge remote-tracking branch 'origin/master' into nexus-5348-purge-persist-data-too
NEXUS-5348: Made method usable in test
NEXUS-5348: Proper UT

That completely covers the purge case how files to
be deleted are collected.