Clean up formatting and make a failure exit non-zero.

Console tools should exit non-zero when a comman fails.

Refs #4993
Remove singularization on schema class names.

Using camelize() does the transformation we want without also
singularizing the name. This makes user input more transparent and fixes
issues around plugin schemas with plural names.

Refs #4993
Merge pull request #5123 from cakephp/issue-4993

Remove singularization on schema class names