BackendModel::getModuleSettings() now accepts a module

This makes working easier
BackendModel::getModuleSetting() can be simplified
Mailmotor settings: use the new functionality from BackendModel::getModuleSettings()
Location: use the new functionality from BackendModel::getModuleSettings()
redefine $module for safety
Bugfix for backend in location index.php
More readable
Merge pull request #562 from siesqo/getModuleSettings

Get module settings now has a $module parameter