Fix various maven pom problems:

- Add relativePath to samples pom.
- Specify versions of plugins

libraries/tools/idl2k/pom.xml

@@ -87,6 +87,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
+                <version>1.2.1</version>
                 <executions>
                     <execution>
                         <id>download-idl</id>

libraries/tools/kotlin-compiler-embeddable/pom.xml

@@ -212,7 +212,7 @@
                 <configuration>
                     <workingDirectory>${project.build.directory}</workingDirectory>
                     <systemPropertyVariables>
-                        <compilerJar>${artifactId}-${parent.version}.jar</compilerJar>
+                        <compilerJar>${project.artifactId}-${project.parent.version}.jar</compilerJar>
                     </systemPropertyVariables>
                 </configuration>
                 <executions>

libraries/tools/kotlin-osgi-bundle/pom.xml

@@ -41,7 +41,7 @@
                         <configuration>
                             <includeScope>compile</includeScope>
                             <includeGroupIds>${project.parent.groupId}</includeGroupIds>
-                            <outputDirectory>${build.outputDirectory}</outputDirectory>
+                            <outputDirectory>${project.build.outputDirectory}</outputDirectory>
                             <excludes>**/MANIFEST.MF</excludes>
                         </configuration>
                     </execution>