Add a lint indicator that replaces Brackets lint indicator

Removes default Brackets lint status indicator.
Replaces the `errorIndicator` with this `lintIndicator`.

See #61 for more detail on the reasons for this. 
What we can do with this function is simple add an attribute, maybe called status.  So, you end up with code like this:

``` javascript
$statusBarIndicator.attr("status", status);
```

``` css
.interactive-linter-lint-indicator[status=error] {
}
```

This will basically remove the need to iterate through the different status in the remove call.