fix: add missing configuration tags

[akadir]

resolves #3

[vifraa]

It looks good 👍

The change won't handle the case where we have lists in the configuration, such as in below. Since the change uses the Properties struct it will only handle String -> String values, key4 below will not be properly handled.

<configuration>
    <key>value</key>
    <key2>value2</key2>
    <key3>value3</key3>
    <key4>
        <tasks>
            <task>task-value</task>
         </tasks>
     </key4>
</configuration>

It is however a step in the correct direction, giving support for the basic cases such as the ones mentioned in issue #3.