goauth2 no longer requires Config to be provided
expand contribution guide a little
mention gocov and gocov-html for test coverage
fix lint error with comments
Add UnauthenticatedRateLimitedTransport

This allows for making unauthenticated requests subject to your
application's rate limit (as opposed to the lower rate limit for
anonymous requests)
more UnauthenticatedRateLimitedTransport tests

add test to check for required fields, as well as test for default vs
custom transport.
rename url_ to u globally

golint doesn't like the underscore in "url_"
add comment for RoundTrip
add test helper methods

add methods for testing request method, request form values, and URL
parse error
Add basic issues related methods

This adds basic methods for working with issues, assignees, and issue
comments.  Issue events, labels, and milestones are not included in this
commit. (Fixes #7)
add docs for issue options
update LICENSE to include GitHub CC-BY license

fixes #11
first pass at pull request methods

This includes most API methods on pull requests (with the exception of
listing commits and the merge functions), as well as all of the methods
for pull request comments. (Fixes #13)

This also fixes a few oversights in the issues API.
fix typo in IssueComment and return more API error data
impl and tests for Trees API
try better names `Tree` for the "github tree" and `GitTree` for git trees
SHA/URL could be in a shared struct and embedded, but not sure if worth it