Fix Maven warnings about missing plugin versions

Signed-off-by: Gregor Zurowski <gregor@zurowski.org>

pom.xml

@@ -28,6 +28,9 @@
 		<spring-cloud-config.version>1.4.0.BUILD-SNAPSHOT</spring-cloud-config.version>
 		<spring-cloud-stream.version>Ditmars.BUILD-SNAPSHOT</spring-cloud-stream.version>
 
+		<!-- Plugin versions -->
+		<maven-compiler-plugin.version>3.6.1</maven-compiler-plugin.version>
+		<maven-eclipse-plugin.version>2.10</maven-eclipse-plugin.version>
 		<!-- Sonar -->
 		<surefire.plugin.version>2.19.1</surefire.plugin.version>
 		<sonar.java.coveragePlugin>jacoco</sonar.java.coveragePlugin>
@@ -40,6 +43,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-eclipse-plugin</artifactId>
+				<version>${maven-eclipse-plugin.version}</version>
 				<configuration>
 					<useProjectReferences>false</useProjectReferences>
 					<additionalConfig>
@@ -56,6 +60,7 @@
 			</plugin>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
+				<version>${maven-compiler-plugin.version}</version>
 				<configuration>
 					<source>1.7</source>
 					<target>1.7</target>