Add dependency for parsing zuliprc (#8)

 commons-configuration will be used to parse the zuliprc which can be
 generated by the zulip client.

Author: Markus Keunecke

pom.xml

@@ -140,6 +140,13 @@
 			<version>4.4.1</version>
 		</dependency>
 
+		<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-configuration2 -->
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-configuration2</artifactId>
+			<version>2.10.1</version>
+		</dependency>
+
 		<!-- https://mvnrepository.com/artifact/javax.activation/activation -->
 		<dependency>
 			<groupId>javax.activation</groupId>