pom.xml: updated mysql-connector-java to 5.1.21

@see http://dev.mysql.com/doc/refman/5.1/en/cj-news-5-1-19.html
@see http://dev.mysql.com/doc/refman/5.1/en/cj-news-5-1-20.html
@see http://dev.mysql.com/doc/refman/5.1/en/cj-news-5-1-21.html

No functional changes.

Author: php-coder

pom.xml

@@ -14,7 +14,7 @@
 		<hibernate.version>3.6.10.Final</hibernate.version>
 		<hibernate.validator.version>5.0.0.Alpha1</hibernate.validator.version>
 		<lombok.version>0.11.2</lombok.version>
-		<mysql.connector.version>5.1.18</mysql.connector.version>
+		<mysql.connector.version>5.1.21</mysql.connector.version>
 		<selenium.version>2.25.0</selenium.version>
 		<slf4j.version>1.6.6</slf4j.version>
 		<spring.version>3.2.0.M1</spring.version>