Add progress bar to saving project

[Kaushik-Iyer]

Attempts to solve a part of #707

I don't know if this is the proper way or syntax to use the progress bar for this project, since this is the first time I am using it, but I have tested this locally and it seemed to work

[paulojamorim]

@Kaushik-Iyer

Thanks for the pull request. At this moment I cannot accept it because the interface code is together with the data code (project.py).

Please create a class inside gui/dialogs.py for the dialog. You can submit project information to dialogs class by pubsub.

[Kaushik-Iyer]

Is this the correct way of implementing pubsub? I tested this locally, but my dialog box doesnt close by itself on save completion. I am having to manually click 'Close' button. What am I doing wrong here?