advagg 8.x-3.4

The only significant change here is the addition of the advagg_bundler sub module to the 8.x-3.x branch. It is ready for use with all the same functionality as in 8.x-2.x (and 7x).
Also, quite a few bug fixes. Thanks everyone for the reports, testing and discussion.

All changes since 8.x-3.3:

• #2916193 by NickWilde: JsMinifierUnitTest::testMinifyJsqueeze() fails on Drupal CI with PHP 5.6
• #2915134 by NickWilde, killes@www.drop.org, jojo1028: JSMin+ Doesn't support the use of reserved keywords as object keys Update test to account for now properly processing ajax.js Hopefully the correct deal now.
• #2915134 by NickWilde, killes@www.drop.org, jojo1028: JSMin+ Doesn't support the use of reserved keywords as object keys Update test to account for now properly processing ajax.js
• #2915134 by NickWilde, killes@www.drop.org, jojo1028: JSMin+ Doesn't support the use of reserved keywords as object keys
• #2916944 by NickWilde: CSS Defer functionality doesn't affect external stylesheets
• Advagg Bundler readme and tests. Note most of test disabled due to PR in mink.
• #2915654 by NickWilde, progzy: Deferred CSS feature does not take media attribute into consideration
• Remove some dead code
• Make sure css.combine_media setting is respected when loading cached data
• Test for combining files by media query (will fail)
• #2903100 by NickWilde: Reimplement bundler in 8.x-3.x
• #2902093 by lvbeck, NickWilde: Advagg generate lot of empty files in root of public file directory