Bumping grip dependency for swift 4.1 compatibility

The allow cache tag was deprecated. Removing it because the validator…

… is throwing errors

Changing how the timescale is configured with audio and video tracks

Updating to use all the new grip data structures

Updating the project to use the new grip data structures

VOD playlists should be marked as cacheable

Merge pull request #5 from krad/flushing

Adding support for flushing out buffers we hold on to

Bumping grip version

Explicity adding the .git to the Package dependency

Merge pull request #4 from krad/move-network-structs-outside-of-project

Hacking up the project to use grip.  This will enable sharing of netw…