Re-re-bundle vendor/listen.

The mkrf_conf strategy didn't work; it caused considerable
installation pain for many users, especially those on Windows.

Closes #1163
Listen 2.7.0 compatibility.

Closes #1151
Work around a bug in Pathname#cleanpath.

Closes #1159
Fix the argument order of a call() example.

Closes #1158
Avoid errors from listen trying to write to read-only directories.
Add changelog entries.
Fix a rubocop error.
Bump VERSION to 3.3.1.
Merge branch 'stable'

Conflicts:
	VERSION
	doc-src/SASS_CHANGELOG.md
Merge remote-tracking branch 'origin/master'
Fix a Listen loading bug.
Bump VERSION to 3.3.2.
Merge branch 'stable'

Conflicts:
	VERSION
	doc-src/SASS_CHANGELOG.md