move to v4 with access token
remove use of v4 API & tokens
update changelog for 0.5.0
bump podspec
bump version
formatting
use Apple-preferred availability macros
add overlay delegate callback for render completion
formatting tweaks
rename state for clarity
move delegate adoption check to point of need
Revert "remove use of v4 API & tokens"

This reverts commit fab6d479b1097c42fb9168d6f04a49c6f0ebd127.
fixes #130: bring back v4 & access token support for iOS 8+
fix typo
flag as bug
better checks & docs on setting zoom
support retrieving zoom
add icons & archive burning
clean up icons & launch screen
burn proper icons