0.2.1
=====

- Add new "nameregistry" helper.  Another fixture
  derived from Beaker, this allows the ad-hoc creation of 
  a new Dogpile lock based on a name, where all other
  threads calling that name at the same time will get 
  the same Dogpile lock.  Allows any number of
  logical "dogpile" actions to carry on concurrently
  without any memory taken up outside of those operations.

- To support the use case supported by nameregistry, added
  value_and_created_fn to dogpile.acquire().  The idea 
  is that the value_and_created_fn can return 
  (value, createdtime), so that the creation time of the 
  value can come from the cache, thus eliminating the 
  need for the dogpile lock to hang around persistently.

- expire time of None means "never expire".

0.2.0
=====

- change name to lowercase "dogpile".

0.1.0
=====

- initial revision.