Update README.md

Merge pull request #40 from t27/master

Updated tests to actually query the database and verify the updates to a hash

Merge pull request #39 from t27/master

Fix to enable mongoose to reliably store and persist updates

fix to make the URL and data keys optional during update

Merge pull request #38 from t27/master

Modified README to include docs for updating hashes

Merge pull request #1 from edwardhotchkiss/master

[minor, changelog] updated and such

[dist, contribs] bumped v, added @t27 to contribs

Merge pull request #37 from t27/master

Added an update call to update the URL or data of a preexisting hash

Merge pull request #34 from datermine/patch-2

Fix bug with missing update var & unnecessary update.