finish draft of chinese language translation, following pch957's request

1. On windows, to test the result, need to copy keyhotee_zh_CN.qm to the same folder of EXE. 
Translations can be loaded from Qt resources, so it is a good idea to bundle them inside your executables. This could be next TODO deserve to implement using CMake.

2. Strings in cpp files are also translated, so following ui files need to be updated later, add cpp files

file(GLOB ui_files *.ui profile_wizard/*.ui AddressBook/*.ui Mail/*.ui)

3. Using lupdate file to generate .ts files:
cd keyhotee/translations
lupdate .. keyhotee_zh_CN.ts
using Linguist to translate, also useful for writer to review.