Update plugins with bugfixes

  - vp8parse: Minor codding style fixes
  - vp8parse: Set DELTA_UNIT flag correctly
  - agnosticbin: Do not wait for tees to have media, use them directly
  - agnosticbin: Set live latency to downstream elements
  - agnosticbin: Avoid linking queue to tee more than once
  - webrtcendpoint: Fix memory leak
  - webrtcendpoint: Use different temporal directories for each webrtcendpoint
  - Prepare for next development iteration

Change-Id: I30808c166c9434fc405eece0ef796ce3b623438a