Test against testpypi.pytyon.org

Added instructions and artifacts required to test against the PyPI test
server. Also did some minor API refactoring.

This plugin was successfully validated against the test PyPI server.

main.go

@@ -14,6 +14,7 @@ import (
 	"github.com/drone/drone-go/plugin"
 )
 
+// Params desribes how to upload a Python module to PyPI.
 type Params struct {
 	Distributions []string `json:"distributions"`
 	Password      *string  `json:"password,omitempty"`
@@ -28,25 +29,28 @@ func main() {
 	plugin.Param("vargs", &v)
 	plugin.MustParse()
 
-	err := deploy(&w, &v)
+	err := v.Deploy(&w)
 	if err != nil {
 		log.Fatal(err)
 	}
 }
 
-func deploy(w *drone.Workspace, v *Params) error {
-	err := createConfig(v)
+// Deploy creates a PyPI configuration file and uploads a module.
+func (v *Params) Deploy(w *drone.Workspace) error {
+	err := v.CreateConfig()
 	if err != nil {
 		return err
 	}
-	err = uploadDist(w, v)
+	err = v.UploadDist(w)
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
-func createConfig(v *Params) error {
+// CreateConfig creates a PyPI configuration file in the home directory of
+// the current user.
+func (v *Params) CreateConfig() error {
 	f, err := os.Create(path.Join(os.Getenv("HOME"), ".pypirc"))
 	if err != nil {
 		return err
@@ -61,7 +65,8 @@ func createConfig(v *Params) error {
 	return nil
 }
 
-func uploadDist(w *drone.Workspace, v *Params) error {
+// UploadDist executes a distutils command to upload a python module.
+func (v *Params) UploadDist(w *drone.Workspace) error {
 	cmd := v.Upload()
 	cmd.Dir = w.Path
 	cmd.Stdout = os.Stdout
@@ -100,7 +105,7 @@ password: %s
 	return err
 }
 
-// Upload creates a setuptools upload command.
+// Upload creates a distutils upload command.
 func (v *Params) Upload() *exec.Cmd {
 	distributions := []string{"sdist"}
 	if len(v.Distributions) > 0 {