Merge changes I688490ff,I267176cc,Ib0c1b40d,I8e211592,Iec165991

* changes:
  Unpack JARs for running servers in $site_path/tmp
  Support serving static/ and Documentation/ from plugins
  Allow plugins.checkFrequency = 0 to disable scanner
  Execute plugins from a copy in $site_path/tmp
  Atomic replace SSH and HTTP bindings during plugin reload