GER-869: Fixing paths in template for gerrit service file
GER-869: Fixing paths in template for gerrit service file

Gerrit_install_directory is over written by GERRIT_ROOT
in the installer so will always be top of gerrit installation.

Change-Id: I9c1a5cd01f74bbdaef00402982c26c341018ad80

WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit