[add] add tests for ranklist_plugin
	new file:   ranklist_plugin/local_test.sh
[modify] change plugin files name, and add a new method to ranklist plugin
	rename:   RanklistAction.lua -> Ranklist.lua
[modify] fix a mistake, give a dot when import a lua file
	modify:     init.lua
[modify] as a plugin, Ranklist don't need base class.
	modify:     Ranklist.lua
[modify] remove a slash, when using "sed" to modify conf file.
	modify:     install_ubuntu.sh