Prevent wiki formatting in test runner variables

Hi there,

I ran into issues because my command variables were being parsed to wiki content:

> !define SERVER_START_COMMAND {java -cp /.../server.jar **ServerRunner**}

...ended up running as:

> java -cp /.../server.jar **ServerRunner &lt;a title="create page" href="HttpTestSuite.ServerRunner?edit&nonExistent=true"&gt;[?] &lt;/a&gt;**

I changed the example values to literals with `!- block-content -!`. Hopefully this will help newcomers prevent accidental formatting.