Increased version to 0.8.5.dev1 after release of 0.8.4.

(commit by unleash 0.5.8.dev1)
Use UrlMixin, instead of UrlKeyValueStore.
Updated docs for UrlMixin.
update comment for new pep8 standards
Another draft for the outer TTL-mixin interface.
Added mental note.
Added note that ValueErrors will be raised.
Check if key is valid as expected.
Defer to _put_file and _put_filename like KeyValueStore does.
Default implementations for _put, _put_file and _put_filename.
Fix (nonrelevant) MRO.