Add changelog before initial release (#24)

CHANGELOG.md

@@ -0,0 +1,18 @@
+# CHANGELOG
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+## Unreleased
+
+## [0.1.0] - 2017-11-16
+
+### Added
+
+- extract `promptui` from [torus](https://github.com/manifoldco/torus-cli) as a
+  standalone lib.
+- `promptui.Prompt` provides a single input line to capture user information.
+- `promptui.Select` provides a list of options to choose from. Users can
+  navigate through the list either one item at time or by pagination