Missing ".git/info/excludes" support

[FezVrasta]

Brackets Git doesn't include the directives stored inside .git/info/excludes, it should add them to the list of gitignore directives.

Git Tower (and other Git IDEs) all have support for it and allow to edit it, I'd love to have at least a basic support for it (making Brackets Git ignore the files inside .git/info/excludes).

Here some more info about how it works:

• https://git-scm.com/docs/gitignore
• https://help.github.com/articles/ignoring-files/#explicit-repository-excludes
• http://stackoverflow.com/questions/10066749/git-excludes-vs-ignores