tools: disallow extra blank lines at EOF/BOF

Enabling linting to disallow extra blank lines at the start or end of
JavaScript files in our code base.

Fixes: https://github.com/nodejs/node/issues/8918
PR-URL: https://github.com/nodejs/node/pull/8920
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

.eslintrc

@@ -80,7 +80,7 @@ rules:
   max-len: [2, 80, 2]
   new-parens: 2
   no-mixed-spaces-and-tabs: 2
-  no-multiple-empty-lines: [2, {max: 2}]
+  no-multiple-empty-lines: [2, {max: 2, maxEOF: 0, maxBOF: 0}]
   no-tabs: 2
   no-trailing-spaces: 2
   quotes: [2, single, avoid-escape]