Add static directory configurations for plugin's ui

Plugin needs static directory configuration for ui requirements,
such as css, js, etc,  as what we do for kimchi base.  So this
patch refactors the server configuration to make plugin can share
the same code with kimchi. To avoid the warning messages reported from
cherrypy's path checker, it also adds empty ui directory for the
sample plugin,  which also can demonstrate plugin's ui directory
sturcture. We can add actual ui files under those direcotries later.

Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Add test case for kimchi server configuration.

To make sure kimchi server has the same configuration as what we
defined in Server class,  this patch copies the original configuration
code and verify it's equal to what's generated from KimchiConfig class.

Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>