Message tweaks

Fix #19.
Refs #18.

Some discussion on @XhmikosR's fork is here: https://github.com/XhmikosR/grunt-bootlint/commit/50ee2809589dfa2dd98041ec6a155cd4f3a0eeb7
This is definitely redundant.

```
Running "bootlint:files" (bootlint) task
No Bootlint errors!

Done, without errors.
```