Reduce package size

[jugglinmike]

We've received a couple reports (gh-3316 and gh-3318) that the installation size of JSHint increased drastically in the recently-released version 2.9.6. This is easily verified using npm's --production flag:

mkdir nodemods
git checkout 2.9.5
npm install --production
mv node_modules nodemods/2.9.5
git checkout -- package.json
git checkout 2.9.6
npm install --production
mv node_modules nodemods/2.9.6
du -h -d 0 nodemods/*

Output:

9.9M    nodemods/2.9.5
277M    nodemods/2.9.6

Two independent commits contributed to this 20-fold increase in side. This patch addresses each of them in turn. You can verify using the same technique:

git checkout shrink-deps~
npm install --production
mv node_modules nodemods/2.9.6-phantom
git checkout -- package.json
git checkout shrink-deps
npm install --production
mv node_modules nodemods/2.9.6-phantom-unicode
du -h -d 0 nodemods/*

Output:

9.9M    nodemods/2.9.5
277M    nodemods/2.9.6
149M    nodemods/2.9.6-phantom
18M     nodemods/2.9.6-phantom-unicode

The final size is still twice that of the prior release, but that is due to the upgrade to Lodash 4 (gh-3260 and gh-3283).

9.9M    nodemods/2.9.6-phantom-unicode-lodash

Since that was motivated by security concerns, I'm more willing to accept the size increase. If this continues to be a concern for our consumers, we can consider instead relying on Lodash's sub-components.

Also of interest: the remove-dev-dependencies.js introduced here is not technically necessary on TravisCI because JSHint can now be successfully be installed in TravisCI on Node 0.8 and 0.10. That's surprising because this was all motivated by failures in TravisCI back in November. At first, I thought that maybe the maintainers of requests had changed their tune, but no such luck. TravisCI now pre-installs PhantomJS, so the offending ES2015 code (used to fetch the binary) is no longer evaluated on any GNU/Linux build. However, we're not so lucky in the AppVeyor-provided Windows environment (and even if we were, we probably shouldn't rely on implicit aspects of the build environments). That's why I've written a script to manually remove the offending packages prior to installation in CI.

I'd like to release a new version (i.e. 2.9.7) for this changeset so that we can help our consumers avoid the inefficiency as soon as possible.

[coveralls]

Coverage remained the same at 98.755% when pulling 7806524 on jugglinmike:shrink-deps into d5c1a00 on jshint:master.

[rwaldron]

Wow, nice work to solve this!