Fix failing build when not executing up to package

metafacture-runner attempted to unpack the metamorph artifact in the
`generate-resources` phase. However, if Maven was invoked with a
lifecycle phase before the the `package` phase, the metamorph artifact
does not exist in the reactor and the build fails. This commit moves the
unpacking of the metamorph artifact into the package phase to solve
the problem.

Author: cboehme

metafacture-runner/pom.xml

@@ -257,13 +257,19 @@
 				</executions>
 			</plugin>
 
+			<!-- The maven-dependency-plugin must appear before the
+			     maven-assembly-plugin in the pom to ensure its unpack goal is
+			     executed before building the assembly.
+
+			     Maven executes goals bound to the same phase in the order in
+			     which the plugins are listed in the pom. -->
 			<plugin>
 				<artifactId>maven-dependency-plugin</artifactId>
 				<version>2.10</version>
 				<executions>
 					<execution>
-						<id>unpack-schemata</id>
-						<phase>generate-resources</phase>
+						<id>add-xsd-schemas</id>
+						<phase>package</phase>
 						<goals>
 							<goal>unpack</goal>
 						</goals>