git: update git shortcuts

Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
vim: update vim submodules and _vimrc

Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
gitignore: add ignored files in _vim

Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>