Make sure certain paths/files don't make it into the dist zip
Don't build the content shell test_runner
Make sure libffmpeg.dylib gets put in the right place
Run verify-ffmpeg on Mac builds
Add ffmpeg build to VSTS
* build: [gn] add distributable zip target
* build: update the CircleCI config
- enable debug and testing builds on Mac
- run Mac release builds nightly
- run test for Mac release builds
- use shared build machines configs
* Add resources dir to zip on non mac platforms.