[TAP,UWS] Ensure the compatibility with Java 7 in the ANT and Gradle scripts.

build.gradle

@@ -38,3 +38,7 @@ test{
 
 sourceSets.main.java.srcDirs = ["src"]
 sourceSets.test.java.srcDirs = ["test"]
+
+/* Set the minimum Java version compatibility: */
+sourceCompatibility = '1.7'
+targetCompatibility = '1.7'

buildADQL.xml

@@ -35,6 +35,10 @@
 		<condition><not><isset property="JUNIT-API"/></not></condition>
 	</fail>
 	
+	<!-- JAVA VERSION COMPATIBILITY -->
+	<property name="ant.build.javac.source" value="1.7"/>
+	<property name="ant.build.javac.target" value="1.7"/>
+	
 	<!-- CLASSPATHS -->
 	<path id="adql.classpath">
 		<pathelement location="${POSTGRES}" />

buildUWS.xml

@@ -41,6 +41,10 @@
 		<condition><not><isset property="SERVLET-API"/></not></condition>
 	</fail>
 	
+	<!-- JAVA VERSION COMPATIBILITY -->
+	<property name="ant.build.javac.source" value="1.7"/>
+	<property name="ant.build.javac.target" value="1.7"/>
+
 	<!-- CLASSPATHS -->
 	<path id="uws.classpath">
 		<pathelement location="${commonsIOJar}" />