switch to version.joni property

Author: stevehu

pom.xml

@@ -65,6 +65,7 @@
         <version.jackson>2.10.0</version.jackson>
         <version.slf4j>1.7.25</version.slf4j>
         <version.common-lang3>3.5</version.common-lang3>
+        <version.joni>2.1.31</version.joni>
         <version.logback>1.2.3</version.logback>
         <version.junit>4.12</version.junit>
         <version.mockito>2.7.21</version.mockito>
@@ -90,7 +91,7 @@
         <dependency>
             <groupId>org.jruby.joni</groupId>
             <artifactId>joni</artifactId>
-            <version>2.1.31</version>
+            <version>${version.joni}</version>
         </dependency>
         <dependency>
             <groupId>ch.qos.logback</groupId>