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

*  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.

    http://stackoverflow.com/questions/4034158/loading-qm-file
    https://code.google.com/p/texworks/source/browse/trunk/CMake/Modules/TranslationMacros.cmake?spec=svn1349&r=1349

*   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)

*   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.