Deprecate Mapper#mapPackage()

[evanchooly]

Move this to the config file and document it. The property should be named morphia.map-packages to support mapping multiple packages. If morphia.map-subpackages is set true, this should provide essential coverage of all mapping needs. If the element is missing this will result in a full classpath scan which is less than ideal and should be prominently documented.

Deprecate #map(Class...) and #map(List<Class>) as well. This effectively makes the package the only granularity for mapping entities.