[REFACTOR] moved inflate/deflate util methods

They were only used in one place.

Change-Id: If0b9351f35e8730d49c5232c80f18c9ed6f2278a
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1314
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>