RPM Support

This story builds off of the whitelist importer option introduced in #206 and adds an option to include dependencies. In #206 the 'whitelist' attribute expects a list as the value. This story maintains the list-style, but introduces a dictionary style value with the keys "packages" which contains the list of names similar to the value of #206 and "include_deps" which will be a boolean to enable the inclusion of dependencies of whitelist items. If include_deps is not specified it defaults to false.

{
    "whitelist": {
        "packages": [
            "foo",
            "bar"
        ],
        "include_deps": true
    }
}

Dependency solving should be done in its own logic that is separate from the rpm sync code itself. It will need to be called from the sync code which implements #206.