Allow copy operations to suppress layouts.

Added support for the [suppressLayouts](http://www.jfrog.com/confluence/display/RTF/Artifactory+REST+API#ArtifactoryRESTAPI-CopyItem) parameter which allows copying to arbitrary locations instead of trying to map artifacts to a layout.

For example, if you want to copy a number of artifacts from a maven repository to a new repository which only serves a flat listing of jar files from different organizations or modules this parameter is required.