Basic fixes for Windows #354

1. Add cl.bat in codalab\bin. Note that the CL name may not be the best on Windows since the Visual C++ compiler uses CL.EXE to compile and link.

2. Editing worksheet and bundle metadata:
    - Make notepad default editor on Windows
    - Use os.linesep instead of '\n'
    - Changes around temp file creation to ensure the file is not locked and is available to edit.
    - getppid returns a constant on Windows until a working substitute is working.

3. Bundle metadata: bundle size changed from int to long.

4. Client config: skip reading config file if it doesn't exist. This is not a complete fix. Commands such as get_host don't work without the config file.

5. Tests: All but 3 are passing. The 3 failures are:
    - test_check_for_symlinks
    - test_hash_file_contests
    - test_set_permissions