fix selenium test imports
actually have a version #249
show web-interface version. fixes #249
preview info on startpage. fixes #246
more preview explanation and cleanup

relates #235, #231, #208
show recommended number of max open files for ES
don't underline notification badge on hover
changed style of sidebar menu. fixes #252
cleaned up stuff, moved stuff, preview hints
Merge git://github.com/Graylog2/graylog2-web-interface into develop