only generate one project.pom.asc

When deploying a relase with the 0.2 version on gradle 1.4 I always get an Error like

    Uploading: com/github/signed/jvm-protocol-handler/jvm-protocol-handler/0.0.2/jvm-protocol-handler-0.0.2.pom.asc to repository remote at http://localhost:8081/nexus/content/repositories/releases
    Transferring 0K from remote
    Uploaded 0K
    Uploading: com/github/signed/jvm-protocol-handler/jvm-protocol-handler/0.0.2/jvm-protocol-handler-0.0.2.pom.asc to repository remote at http://localhost:8081/nexus/content/repositories/releases
    Transferring 0K from remote
    :uploadArchives FAILED

    FAILURE: Build failed with an exception.
    * What went wrong:
    Execution failed for task ':uploadArchives'.
    > Could not publish configuration 'archives'
    > Error deploying artifact 'com.github.signed.jvm-protocol-handler:jvm-protocol-handler:jar': Error deploying artifact: Failed to transfer file: http://localhost:8081/nexus/content/repositories/releases/com/github/signed/jvm-protocol-handler/jvm-protocol-handler/0.0.2/jvm-protocol-handler-0.0.2.pom.asc. Return code is: 400

The log states, that after the first successfull upload of jvm-protocol-handler-0.0.2.pom.asc the attempt to upload the file a second time failed. The second attempt to upload the file occures, because the pom.asc file is actually generated two identical pom.asc files.

With this patch the plugin only generates only one pom.asc file.