Surface sass errors

Right now, if there are any errors compiling sass, the only notification is an error code.

```
[gulp] Error in plugin 'gulp-ruby-sass': Exited with error code 1
```

This pull request surfaces the errors with more detailed debugging information.

```
[gulp] Error in plugin 'gulp-ruby-sass': 
Syntax error: Invalid CSS after "}": expected selector or at-rule, was "{"
        on line 22 of /redacted-path-to-file/style.scss
  Use --trace for backtrace.
```