Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

env/dirs.go

@@ -0,0 +1,23 @@
+package env
+
+import "path/filepath"
+
+func (dis Distillery) BackupDir() string {
+	return filepath.Join(dis.Config.DeployRoot, "backups")
+}
+
+func (dis Distillery) RuntimeDir() string {
+	return filepath.Join(dis.Config.DeployRoot, "runtime")
+}
+
+func (dis Distillery) RuntimeUtilsDir() string {
+	return filepath.Join(dis.Config.DeployRoot, "runtime", "utils")
+}
+
+func (dis Distillery) InprogressBackupPath() string {
+	return filepath.Join(dis.BackupDir(), "inprogress")
+}
+
+func (dis Distillery) FinalBackupPath() string {
+	return filepath.Join(dis.BackupDir(), "final")
+}