Use cuttlefish API funcs for future-proofing

Using element/2 is a bit opaque and could break in the future if the
record format changes.
Improve mapping type specs in clique_config
Display config vals of type 'flag' correctly

When using the "show" command to display config values, we now display
config values of type 'flag' using the correct user-facing values
(typically "on" and "off") instead of the internal true/false value.

This fixes issue #20.
Fix double-negative bug in flag code
Merge pull request #27 from basho/feature/show-cuttlefish-flag-values

Display config vals of type 'flag' correctly