Added release date.
Fixed bug#8719 - PasswordMin2Lower2UpperCharacters problem.

Conflicts:
	CHANGES.md
Added note about bugfix.
upped version number in CHANGES
Improved UT to modify a writable file.
Merge branch 'rel-3_1' of git.otrs.com:otrs/otrs into rel-3_1
Fixed exit calls.
Corrected exit status handling.
Fixed bug#9104 - Group permission for customer subset overwrites permissions for other customers.
Improved parameter quoting in various places.

Conflicts:
	Kernel/System/CustomerCompany/DB.pm

Conflicts:
	CHANGES.md
Fixed bug#[9011](http://bugs.otrs.org/show_bug.cgi?id=9011) - GenericInterface: New value after value mapping can't be 0.
Fixed bug#9557 - Cannot see quoted text in customer ticket zoom.
Merge branch 'rel-3_1' of git.otrs.com:otrs/otrs into rel-3_1

Conflicts:
	CHANGES
Fixed bug#8273 - Copying text in preview mode not possible.
Fixed bug#9125 - AgentTicketSearch dialog does not expand when choosing more search criteria.