Fetching initial branch(es) should be part of fetch project step

[Alex Launi]

This bug is similar to lp:518583, but I was told to file a new bug.

As it stands, the current workflow for getting started working on a new project is a bit confusing. I was surprised when I went into my project folder for the project I just fetched that there was no code. I actually thought it was broken, so I deleted the folder and tried again. The second time I saw the "fetch branch" button, and realized I had to get the code manually.

Clearly if you're fetching a project you'll want to fetch a branch as the next step, so this process should be streamlined so that when the opportunistic developer fetches a project, he/she can get to work immediately.

I think that the workflow should change to the following -->
 * Fetch Project
   * Chose project
     * GC presents a list of branches, the same that would be presented in the "Fetch Branch" step
       * GC creates project directory, branches inside, and returns to nautilus in the newly created branch directory.