Display current project title in main window

This succeeds #6878 This adds #2281, displaying the project name in the Brackets window title.

Issues remaining:

- [ ] If Brackets loads to a project with no working files open, it will display "null - Brackets" in the title bar. This is what I was trying to report in #7206, but as stated in https://github.com/adobe/brackets/issues/7206#issuecomment-38097165, I probably need to add an `AppInit.appReady()` section to fix this (there is not one already, and moving the relevant lines under `AppInit.htmlReady()` does not do it). Screenshot:

![brackets-null-title](https://cloud.githubusercontent.com/assets/3382464/2921116/6eb80988-d6ef-11e3-951d-3257a3c3c019.png)

- [ ] Upon switching from a project with no working files to a project with working files then back to the first one, the previous project name will shown until a working file is made or just a file is opened (but not made a working file). I'm not sure how to fix this one. Example (shows both issues):

![brackets-title-bugs](https://cloud.githubusercontent.com/assets/3382464/2921208/8f82f96a-d6f0-11e3-8c37-dce59c12cb08.gif)

This is on Windows 8.1 Update 1 x64 using Brackets at 83db92cf2f78324e197b2e93944cd2e38399440a, if that matters.