Release bt/v0.5.0

== v0.5.0: New features

* Better cache invalidation.

* Suggest workspace completions rather than limiting the list of valid values.

* New command: `bt terraform providers lock`
+
Uses the config file to get the list of archs for the given profile and uses them to update the lock file.

* Add support for missing terraform commands:

** state mv
** validate
** test