Support strings as bool values in shorthand syntax

When using shorthand syntax, bool types are passed as
a string value, so we need to support "true" and "false".

This is fairly conservative in that, it's either exactly
"[Ff]alse", otherwise it's True.  We could require more
strict checking though if we want.
Merge branch 'fix-bool-shorthand-parse' into develop

* fix-bool-shorthand-parse:
  Support strings as bool values in shorthand syntax