To start with, the jar that I need to connect to MySQL 5.5 should have been mysql-connector-java-5.1.15-bin.jar but not mysql-connector-java-5.1.15.jar. Secondly, this jar is not available in maven repository so I needed to manually add it to my local maven repository and then added it as a dependency in my pom.xml.
Adding mysql-connector-java-5.1.15.jar to the local maven repository by mvn install:install-file -Dfile=C:\Libraries\mysql-connector-java-5.1.15-bin\mysql-connector-java-5.1.15-bin.jar -DgroupId=mysql -DartifactId=mysql-connector-java -Dversion=5.1.15-bin -Dpackaging=jar and then adding the following dependency to pom.xml of the project.
<!-- MySql 5.5 Connector -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.15-bin</version>
</dependency>