Add changes for 0.19.0 to the CHANGELOG

The items are based upon the commits between 0.18.1 and 0.19.0 that were no
related to things like consistencies in the code (using double quotes for
example), docs, and specs.

Author: Brett Chalupa

CHANGELOG.md

@@ -1,3 +1,24 @@
+## 0.19.0, release 2014-03-22
+* Add support for a default to #ask
+* Avoid @namespace not initialized warning
+* Avoid private attribute? warning
+* Fix initializing with unknown options
+* Loosen required_rubygems_version for compatibility with Ubuntu 10.04
+* Shell#ask: support a noecho option for stdin
+* Shell#ask: change API to be :echo => false
+* Display a message without a stack trace for ambiguous commands
+* Make say and say_status thread safe
+* Dependency for console io version check
+* Alias --help to help on subcommands
+* Use mime-types 1.x for Ruby 1.8.7 compatibility for Ruby 1.8 only
+* Accept .tt files as templates
+* Check if numeric value is in enum
+* Use Readline for user input
+* Fix dispatching of subcommands (concerning :help and *args)
+* Fix warnings when running specs with `$VERBOSE = true`
+* Make subcommand help more consistent
+* Make the current command chain accessible in command
+
 ## 0.18.1, release 2013-03-30
 * Revert regressions found in 0.18.0