integrates new cache backends and wrappers

docs(changelog): add initial changelog for version 1.2.0

fix(readme): update disk cache hashing algorithm to SHA-256

BREAKING CHANGE: The disk cache hashing algorithm has been changed
from MD5 to SHA-256 for security reasons. Existing caches created
with the original fork (gregjones/httpcache) are not compatible
and will need to be regenerated.