Optimization of modRemoteIP Configuration

With 1.3.0 we introduced

httpd.remoteIPInternalProxies for aem-dispatcher in the variant aem-publish

but we totally missed to implement this for the author variant.

In a recent project we also noticed that it is required to make the
RemoteIPHeader configurable.

With this improvement we should add:

• mod_remote IP support for aem-author

• configuration support for RemoteIPHeader (httpd.remoteIPHeader)