Bug 756 - ExperimenterAction length computation added

Signed-off-by: Michal Polkorab <michal.polkorab@pantheon.sk>
Change-Id: I7b1bc70b4a7f1ca62b0a6530ff2d4b48349e5620
(cherry picked from commit 7b1bc70b4a7f1ca62b0a6530ff2d4b48349e5620)