Fix handling of maven aggregator pom (no artifact or attachments) based projects and nexus (which doesn't allow empty artifacts).

Update to use header instead of not deploying any catalog; Extract GAV coordinate creation into helper factory (+1 squashed commit)
Squashed commits:
[5624233] Fix handling of maven aggregator pom (no artifact or attachments) based projects and nexus (which doesn't allow empty artifacts).

Remove assumption that empty non-pom projects are invalid reusing same behaviour (+3 squashed commits)
Squashed commits:
[5aac3f6] Ensure result of file operations are checked and logged for debugging purposes
[115d257] Minor code optimisations based on project java code level
[2634b62] Fix handling of maven aggregator pom (no artifact or attachments) based projects and nexus (which doesn't allow empty artifacts).

Author: ukcrpb6

pom.xml

@@ -49,6 +49,8 @@
     </scm>
 
     <properties>
+        <maven.compiler.source>1.7</maven.compiler.source>
+        <maven.compiler.target>1.7</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>