prevent submit when permissions are empty

this needs some proper highlighting when validation fails, tough
issue #254
fix quickvalues scrolling. #263
Merge branch 'play' of github.com:Graylog2/graylog2-web-interface into play
up/down positioning for quickvalues. fixes #263
disable editing permissions for preview version

this feature needs a properly working permission/role editor, otherwise it will confuse too much. also there's no help available for now
#issue 255
make minute standard histogram interval. #237
check for application.secret being configured properly

resolves #134
don't warn on successful authentication
add some more preview notices
enabled to delete user accounts
move runtime information about nodes to system resource

fixes #267 by lazily loading system information into Node object
pagination for search results. fixes #235
javadoc failed on this
change app name
bump version to 0.20.0-preview.1
Merge git://github.com/Graylog2/graylog2-web-interface into develop