refactor: move ooni into the internal package (#168)

With this commit we've reorganised the package structure. Now I will
go more in depth and perform further refactoring.

internal/ooni/ooni_test.go

@@ -0,0 +1,29 @@
+package ooni
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"testing"
+)
+
+func TestInit(t *testing.T) {
+	ooniHome, err := ioutil.TempDir("", "oonihome")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(ooniHome)
+
+	ctx := NewContext("", ooniHome)
+	swName := "ooniprobe-cli-tests"
+	swVersion := "3.0.0-alpha"
+	if err := ctx.Init(swName, swVersion); err != nil {
+		t.Error(err)
+		t.Fatal("failed to init the context")
+	}
+
+	configPath := path.Join(ooniHome, "config.json")
+	if _, err := os.Stat(configPath); os.IsNotExist(err) {
+		t.Fatal("config file was not created")
+	}
+}