SCHEMA-197. Layout versions now use the "layout" namespace.

- Changes the expected layout format version to "layout-1.0" or
  "layout-1.1".
- All layouts in resources have had their version numbers changed to
  "layout-1.0" or "layout-1.1".
- Existing layouts with a 'kiji-1.0' version string are supported.
- "kiji version" will now show the minimum and maximum layout versions
  that this kiji version can recognize.

Signed-off-by: Aaron Kimball <aaron@wibidata.com>