First pass at #210
first pass at tests, uncertain about this as well
Convert Release.published_at attribute to a datetime
Add repr to Asset class
Merge pull request #218 from bgilbert/fixes-1

Two small fixes
Abstract file downloading out of Repository.archive()
Drop test fixture for old download API
Add release and asset test fixtures
Add Asset#download and #download_url
Add Asset class to the repos documentation

Also add the Release class to the section index.
Add test for proper IssueEvent.issue

When the issue event JSON is obtained via the "List events for an issue"
API, it does not contain information about the parent issue.  In this
case the second argument to the IssueEvent constructor must be the
parent Issue, but Issue.iter_events() does not arrange for this.  As a
result IssueEvent.issue is bogus and __repr__() breaks.  Add a test for
this case.
Fix IssueEvent construction by Issue.iter_events()

IssueEvents returned by Issue.iter_events() had a bogus "issue"
attribute and thus a broken repr.
Fix encoding bug
Add IssueEvent.actor attribute
Add Milestone.updated_at attribute
Handle unicode in the repr string
Fix truncated attribute documentation
Merge remote-tracking branch 'origin/develop' into develop
A Deployment payload is no longer a string

- See http://developer.github.com/changes/2014-03-03-deployments-api-updates/
Drop unnecessary guards around _strptime calls