CChooseVersion::InitChooseVersion() support to NO block OK button

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
No need to wait for loading branches/tags in Create Branch dialog and Export Dialog

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Show "Loading" while loading branches/tags

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>