Normalize newlines to '\n'

Change all \r\n into unix style newlines. Add missing newlines at the
end of a file and activate the newline checkstyle module, that enforces
'\n' as newline and a newline at the end of every file.
Update README.md
Move EntityCaps and Bookmarks API in correct package

Also move ProviderConfigTest into core, since it tests core
functionality, nothing provided by extensions. Found the reason the test
was failing since the gradle migration (provider entry test.providers),
and activated it again. \o/

New API design as of SMACK-545