build: provide plugins version numbers

maven3 cleanup

pom.xml

@@ -51,6 +51,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>2.0.2</version>
                 <configuration>
                     <source>1.6</source>
                     <target>1.6</target>
@@ -62,6 +63,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
+                <version>1.2</version>
                 <executions>
                     <execution>
                         <goals>