Upgrading version to 0.4.1.

[dhermes]

This is for a Friday minor release cycle.

@tseaver I'll handle pushing the tag as well. Preference for tag names? Current is:

0.3.0
v0.4.0

[coveralls]

Coverage remained the same at 100.0% when pulling e520f98 on dhermes:cut-friday-release-0.4.1 into c6718f3 on GoogleCloudPlatform:master.

[dhermes]

Running

$ git log v0.4.0..e520f98266f5879ec77ef3fb576dabdf87869649 \
> | grep 'Merge pull request ' \
> | awk -F ' ' '{print $4}' \
> | sort

returns

#600
#601
#602
#603
#604
#608
#610
#611
#612
#615
#617
#619
#622
#625
#628
#629
#635

[dhermes]

This is my plan for the release notes on the tag:

-- Adding Python 3.3, 3.4 testing support.
-- Removed 'if bucket in connection' and 'for bucket in connection' syntax.
-- Allowing [custom][1] http object to be used in Connection.
-- Raise exception when default dataset ID can't be inferred.
-- Add Key.__eq__ and Entity.__eq__ in datastore.
-- Fixing issue with datastore.get([]) and stored entities in properties
-- Adding versioned docs

[1]: https://github.com/GoogleCloudPlatform/gcloud-python/pull/608

[tseaver]

I'd prefer it without the v prefix. Your list LGTM.