add lingua.getValue snippet to switch placeholder's value on other snippet

fix default lang value on LinguaRequest
update lingua.selector snippet
fix uri update when alias/parent's alias is changed
modify build to add additional fields into content
fix refreshURIs() and links on lingua's language selector
[#4] fix default lang value on manager's dropdown
[#5] fix update window's URL of language CMP
[#3] move the plugin's setting into System Settings instead
add lingua.getValue into build
init 2.0.0-rc2