Add permissions to teams (google#1864)

Fixes: google#1863.

Author: derekjobst

github/github-accessors.go

@@ -32,6 +32,10 @@ type Team struct {
 	// Permission specifies the default permission for repositories owned by the team.
 	Permission *string `json:"permission,omitempty"`
 
+	// Permissions identifies the permissions that a team has on a given
+	// repository. This is only populated when calling Repositories.ListTeams.
+	Permissions *map[string]bool `json:"permissions,omitempty"`
+
 	// Privacy identifies the level of privacy this team should have.
 	// Possible values are:
 	//     secret - only visible to organization owners and members of this team