add-user.sh scripts change layout of properties files

Description of problem:
add-user.sh scripts change layout of properties files:

• application-users.properties
• mgmt-users.properties

How reproducible:
Always

Steps to Reproduce:

1. get fresh EAP
2. ./add-user.sh -u admin2 -p Admin1** -s
3. ./add-user.sh -a -u admin3 -p Admin1** -s

Actual results:
These comments are moved to the end of application-users.properties file:

#
#$REALM_NAME=ApplicationRealm$ This line is used by the add-user utility to identify the realm name already used in this file.
#

These comments are moved to the end of mgmt-users.properties file:

#
#$REALM_NAME=ManagementRealm$ This line is used by the add-user utility to identify the realm name already used in this file.
#

Expected results:
Comments have same order after execution of add-user.sh

CC: tomazcerar