Prevent nexus from being redeployed and restarted during every chef run when version has not changed

Skip the manifest check for artifact_deploy to prevent an unnecessary redeploy and restart of nexus during every chef run when the nexus version has not changed.

When artifact_deploy does a manifest check, it is detecting a difference every time.  I checked the yaml generated by the artifact cookbook and this is the difference that is causing a nexus redeploy to be triggered on every chef run.

    # diff -w /tmp/saved_manifest.yml /tmp/current_manifest.yml
    6,7d5
    < /nexus/home/releases/2.8.1-01/nexus-2.8.1-01/tmp/nexus-ehcache/shiro-activeSessionCache.index: !binary |-
    <   MzZiZDJjNmI3MjUyNTRiOTY2ZmI4ZmVmODI4YjRmNmY5ZTQxZDI4Mw==

Setting skip_manifest_check to true in the artifact_deploy resource will limit redeployment of nexus to the case when the version actually changes.