Just final bits of test coverage for import/export of LibreOffice. It turns out Travis by default installs an old LO that doesn't support PDF import. To remedy that I use the LO PPA and also strict install the PDF import support.
Still to do in a future date is check LO exported contents includes expected strings, for now it just checks output length looks sane.
1. Introduce contentcollector.js backend tests
1. Fix issue with OL LI items not being properly numbered after import
1. Fix issue with nested OL LI items being improperly numbered on export
1. Fix issue with new lines not being introduced after lists in on import #3961
1. Sanitize HTML on the way in (import)
1. Fix ExportHTML CSS because it needs to support OL > LI > OL not OL > OL [The latter being the correct format]
1. Fix backend tests.
* Remove npm cache from Travis, this was causing a world of pain.
* Remove the broken line attribute tests.
* Do a HTTP get against Etherpad to begin minification.
* Wait 10 seconds after minification before running tests.
