fix(scully): watchMode: fix problem with ghost service in mac

[jorgeucano]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/scullyio/scully/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Other... Please describe:

What is the current behavior?

ScullyServer keeps running even though I quit it with Cmd + C or "q"

Issue Number: #339

What is the new behavior?

Fix this error waiting for kill servers

Does this PR introduce a breaking change?

• Yes
• No

Other information

[SanderElias]

LGTM

[jorgeucano]

@aaronfrost I test in my mac and the fix worked... But, can you test in your computer, i really love to test and check with a mac first user.