Bug 1376128 - Update lint ignore patterns for testing/marionette; r=a…

…utomatedtester,standard8

We want to ignore a certain subset of generated and legacy code
in testing/marionette, most notably testing/marionette/atom.js and
testing/marionette/legacyaction.js.  Since the latter is scheduled for
removal, there is no need to spend extra time linting it.

MozReview-Commit-ID: OyRoM2uigG

.eslintignore

@@ -301,8 +301,14 @@ security/nss/**
 services/sync/modules/constants.js
 services/sync/services-sync.js
 
-# testing/ exclusions
-testing/marionette/**
+# Remote protocol exclusions
+testing/marionette/test_*.js
+testing/marionette/atom.js
+testing/marionette/legacyaction.js
+testing/marionette/client/**
+testing/marionette/harness/**
+
+# other testing/ exclusions
 testing/mochitest/**
 # third party modules
 testing/modules/ajv-4.1.1.js