[sugar] Improve ActivityFactory utility functions and reduce code-path duplication.

[Marco Pesenti Gritti]

On 11/5/07, Michael Stone <michael at laptop.org> wrote:
>   * Remove a race in open_log_file()
>
>   * Make open_log_file return a path as well as a file-object so that
>     Rainbow-launched activities can log to the same path that sugar-launched
>     ones do.
>
>   * Change the call to Rainbow so that it writes to the log-file provided by
>     open_log_file()
>
>   * Define SUGAR_BUNDLE_ID env variable and change the location of the check
>     for /etc/olpc-security so that Rainbow doesn't have to search for or parse
>     the activity bundle.
>
>   * Remove import statements marked as unnecessary by pylint.
>
>   * Fix up some whitespace issues.

Patch looks good to me. Please check it in. (make sure to have release
team approval though).

Thanks!
Marco