cleanup server statistics page; remove unused .js and .css files; fix the sortable table; add new columns
fix problem with usage statistics updating when there are no longer available resources after syncronization
Merge remote branch 'upstream/master'
Merge pull request #724 from cgirardi/master

Fix usage statistics information
fix error with X-Forwarded-For headers with multiple IP addresses

We have to make sure here that the `_get_ipaddress` function returns at
most one IP address.