remove valve on shutdown, otherwise it will remain on the main container
additional check of requested context on host level
updated tomcat versions
fixed tests on RequestTrackingHostValve
Merge branch 'fixes' of git://github.com/h0nIg/memcached-session-manager into h0nIg-fixes
Merge branch 'tomcat_update' of git://github.com/h0nIg/memcached-session-manager into h0nIg-tomcat_update