Update changelog.

Merge pull request #10 from Unity-Technologies/delaycall-fix

Tasks with UI affinity are now invoked faster.

Make sure tasks controlled by the Downloader can be cancelled

Fix build, grrr

Fix ProcessTaskList throwing away results

Fix build

Bump to 2.0.0-preview

yamato: simplify job dependencies

Fix bug in BaseOutputProcessor default string processing

Add process tasks that return lists of data