Updating managing directors

This commit serves to make changes requested as part of [team-navy Issues travis-ci#10 — Change Imprint, letter and invoice footer about changed managing director](https://github.com/travis-pro/team-navy/issues/10). This change removes Joshua Kalderimis and moves the managing directors to be in alphabetical order by surname: Mathias Meyer, and Fritz Thielemann.

imprint.md

@@ -12,7 +12,7 @@ permalink: /imprint.html
     Germany
   </address>
   <h4>Vertreten durch</h4>
-  <p>Josh Kalderimis, Mathias Meyer</p>
+  <p>Mathias Meyer, Fritz Thielemann</p>
   <h4>Kontakt</h4>
   <p>
     Email [email protected] <br>