fix links

README.md

@@ -1,8 +1,5 @@
 # Library THM Core
 
-<a href="http://icampus.thm.de"><img src="documentation/iCampus Development Guide/images/iCampusLogo_V2.png"
-alt="Homepage of iCampus"height="180" /></a>
-
 A library which contains several functions for all sub-projects.
 
 In all software there are mistakes that need to be fixed. The source
@@ -13,9 +10,7 @@ page explains how you can contribute to the iCampus projects by testing
 proposed solutions or sending change requests. You do not need to have
 any coding knowledge, you do need a Joomla installation to test on.
 
-<a href="http://icampus.thm.de/jira/issues/"><img src="documentation/iCampus Development Guide/images/issues_button.png"
-alt="Issues"height="80" align="center"/></a>
-</br>
+[Jira Issue Tracker](http://icampus.thm.de/jira/issues/)
 
 # Overview
 An overview of the iCampus development infrastructure is available at