Allows settings to be overwritten on a per-project base

[fcoury]

If you create a settings area on your Project.sublime-project file and you override settings of the original RubyTest.sublime-settings file, it will read the properties from that file that instead.

Example (used on a Rails 3.2 project that uses Spring binstubs for RSpec):

{
    "folders":
    [
        {
            "follow_symlinks": true,
            "path": "crm_bliss"
        }
    ],
    "settings":
    {
        "run_rspec_command": "bundle exec bin/rspec {relative_path}",
        "run_single_rspec_command": "bundle exec bin/rspec {relative_path}:{line_number}",
    }
}