Feature request: support interactive git stash

Current behavior:
git stash stashes whatever is tracked, but not committed with an auto-generated message.

Feature request:

git stash supports the following features

1. useful message

git stash push -m "human-readable message"

2. stash specific file(s)

git stash push -- file1 file2

3. stash untracked files

git stash push --include-untracked

All these can be supported in qt creator (just like git commit editor).