Bump version to 0.3.4 and update Changelog

Change-Id: If3438662c4b40adab912dcba48029ad36135ff60
diff --git a/pom.xml b/pom.xml
index fc63426..f5796b3 100644
--- a/pom.xml
+++ b/pom.xml
@@ -4,7 +4,7 @@
   <groupId>de.ids_mannheim.korap</groupId>
   <artifactId>KalamarExportPlugin</artifactId>
   <packaging>jar</packaging>
-  <version>0.3.3</version>
+  <version>0.3.4</version>
   <name>KalamarExportPlugin</name>
   <url>https://korap.ids-mannheim.de/</url>