Add support for new Projects Preview API

Fixes google#432.

Change-Id: I4792114482f412f0eff54a6899a759fc9393ff88

Author: gmlewis

github/github.go

@@ -87,6 +87,9 @@ const (
 
 	// https://developer.github.com/v3/repos/traffic/
 	mediaTypeTrafficPreview = "application/vnd.github.spiderman-preview+json"
+
+	// https://developer.github.com/changes/2016-09-14-projects-api/
+	mediaTypeProjectsPreview = "application/vnd.github.inertia-preview+json"
 )
 
 // A Client manages communication with the GitHub API.

github/repos_forks.go

@@ -50,7 +50,7 @@ type RepositoryCreateForkOptions struct {
 
 // CreateFork creates a fork of the specified repository.
 //
-// GitHub API docs: http://developer.github.com/v3/repos/forks/#list-forks
+// GitHub API docs: https://developer.github.com/v3/repos/forks/#create-a-fork
 func (s *RepositoriesService) CreateFork(owner, repo string, opt *RepositoryCreateForkOptions) (*Repository, *Response, error) {
 	u := fmt.Sprintf("repos/%v/%v/forks", owner, repo)
 	u, err := addOptions(u, opt)