Build Errors -- missing context

```
$ go get github.com/dutchcoders/gister
# github.com/dutchcoders/gister
go/src/github.com/dutchcoders/gister/main.go:26:35: not enough arguments in call to client.Gists.Delete
have (string)
want (context.Context, string)
go/src/github.com/dutchcoders/gister/main.go:75:36: not enough arguments in call to client.Gists.Create
have (*"github.com/google/go-github/github".Gist)
want (context.Context, *"github.com/google/go-github/github".Gist)
go/src/github.com/dutchcoders/gister/main.go:93:34: not enough arguments in call to client.Gists.Get
have (string)
want (context.Context, string)
go/src/github.com/dutchcoders/gister/main.go:131:34: not enough arguments in call to client.Gists.Get
have (string)
want (context.Context, string)
go/src/github.com/dutchcoders/gister/main.go:159:34: not enough arguments in call to client.Gists.Get
have (string)
want (context.Context, string)
go/src/github.com/dutchcoders/gister/main.go:274:34: not enough arguments in call to client.Gists.Get
have (string)
want (context.Context, string)
go/src/github.com/dutchcoders/gister/main.go:283:34: not enough arguments in call to client.Gists.Edit
have (string, *"github.com/google/go-github/github".Gist)
want (context.Context, string, *"github.com/google/go-github/github".Gist)
go/src/github.com/dutchcoders/gister/main.go:300:36: not enough arguments in call to client.Gists.List
have (string, *"github.com/google/go-github/github".GistListOptions)
want (context.Context, string, *"github.com/google/go-github/github".GistListOptions)
go/src/github.com/dutchcoders/gister/main.go:313:36: not enough arguments in call to client.Gists.List
have (string, *"github.com/google/go-github/github".GistListOptions)
want (context.Context, string, *"github.com/google/go-github/github".GistListOptions)
```

Start with the reported call sites in main.go and run go get github.com/dutchcoders/gister to reproduce the compiler errors. Check the Gists method signatures in the go-github dependency, update each failing call consistently, and confirm that the command builds without these errors.

Written by the indexing model from the issue text.