Line break not inserted before first host — leads to broken lines

MAMP Pro seems to insert its rules at the end of `/etc/hosts` without a trailing line break. vagrant-hostsupdater then adds its rules after without a prepended line break. Thus, two rules get put on one line, and the vagrant-hostsupdater line does not work. I have to manually go in and fix it from time to time.

I would suggest that vagrant-hostsupdater always include a prepended line break.
