Note that this is an API-breaking change but should have minimal
impact on users of this package due to the nice inference
properties of the Go programming language.

Bumped `libraryVersion` to `2` due to API-breaking change as
discussed in #376.

Fixes #180.

Change-Id: Ib386135e6b8f306d1f54278968c576f3ceccc4e7

Fixes #328.

Change-Id: I2f93fb89eb46e9d341e9a9aada8de1b3339d1ffd

Change-Id: Ia4888efa18c557a31af7093cfa449a67650afa20

Change-Id: I013dcbfb58ec10756c7b4e4bae6fe79b5e7c0062
Fixes #287

There's no way of serializing/requesting an empty required_contexts that
is needed for bypassing the commit status checks for the ref.

It's a breaking change but will allow to serialize an empty array and
omit empty value as expected.

Deployments API is now official.

https://developer.github.com/changes/2014-11-25-the-deployments-api-is-official/

Fixes #189.