POM: isolate versions into properties

This allows them to be overridden by tooling on the CLI.

Author: ctrueden

pom.xml

@@ -83,6 +83,13 @@
 		<license.licenseName>apache_v2</license.licenseName>
 		<license.copyrightOwners>Hadrien Mary</license.copyrightOwners>
 		<netbeans.hint.license>apache20</netbeans.hint.license>
+
+		<commons-cli.version>1.4</commons-cli.version>
+		<json-simple.version>1.1.1</json-simple.version>
+		<beaker-kernel-base.version>0.9.1</beaker-kernel-base.version>
+		<jai-imageio-core.version>1.3.1</jai-imageio-core.version>
+		<groovy-json.version>2.5.0-beta-1</groovy-json.version>
+		<xchart.version>3.4.0</xchart.version>
 	</properties>
 
 	<repositories>
@@ -113,40 +120,40 @@
 		<dependency>
 			<groupId>commons-cli</groupId>
 			<artifactId>commons-cli</artifactId>
-			<version>1.4</version>
+			<version>${commons-cli.version}</version>
 		</dependency>
 
 		<!-- Used to create the kernel.json file -->
 		<dependency>
 			<groupId>com.googlecode.json-simple</groupId>
 			<artifactId>json-simple</artifactId>
-			<version>1.1.1</version>
+			<version>${json-simple.version}</version>
 		</dependency>
 
 		<!-- The Beaker base kernel that we rely on -->
 		<dependency>
 			<groupId>com.github.twosigma.beakerx</groupId>
 			<artifactId>beaker-kernel-base</artifactId>
-			<version>0.9.1</version>
+			<version>${beaker-kernel-base.version}</version>
 		</dependency>
 
 		<!-- The package to convert images to PNG/JPEG -->
 		<dependency>
 			<groupId>com.github.jai-imageio</groupId>
 			<artifactId>jai-imageio-core</artifactId>
-			<version>1.3.1</version>
+			<version>${jai-imageio-core.version}</version>
 		</dependency>
-                
+
 		<dependency>
 			<groupId>org.codehaus.groovy</groupId>
 			<artifactId>groovy-json</artifactId>
-			<version>2.5.0-beta-1</version>
+			<version>${groovy-json.version}</version>
 		</dependency>
-                
-                <dependency>
+
+		<dependency>
 			<groupId>org.knowm.xchart</groupId>
 			<artifactId>xchart</artifactId>
-			<version>3.4.0</version>
+			<version>${xchart.version}</version>
 		</dependency>
 
 		<!-- ImageJ packages used in the NotebookService -->
@@ -218,6 +225,5 @@
 			<artifactId>junit</artifactId>
 			<scope>test</scope>
 		</dependency>
-
 	</dependencies>
 </project>