Replace HTML entities in README

This replaces HTML character entities so that the README is rendered better on
Bitbucket.

README.md

 JastAdd2
 ========
 
-JastAdd2 was developed at Lund University by Torbjörn Ekman, Görel
+JastAdd2 was developed at Lund University by Torbjörn Ekman, Görel
 Hedin, and Eva Magnusson. JastAdd2 has recieved additional contributions from
-Emma Söderberg, Jesper Öqvist and Niklas Fors.
+Emma Söderberg, Jesper Öqvist and Niklas Fors.
 
 For additional contributors, see the change logs.