Upgrade ivy to 2.5.0 to use HTTPS for maven downloading

Author: odaira

build.xml

@@ -26,7 +26,7 @@
   <property name="javac.source" value="1.7" />
   <property name="javac.target" value="1.7" />
 
-  <property name="ivy.jar.version" value="2.2.0"/>
+  <property name="ivy.jar.version" value="2.5.0"/>
   <property name="ivy.jar.name" value="ivy-${ivy.jar.version}.jar"/>
   <condition property="ivy.xml.name" value="ivy-pure-java.xml" else="ivy.xml">
     <istrue value="${lz4-pure-java}"/>