Move @types to devDependencies

[ntindall]

This causes issues for some versions of npm-shrinkwrap.

[jjrv]

Hi,

thanks for the PR! What sort of issues do you refer to? The @types are in dependencies for cases where cxml is used in a TypeScript project. Its type definitions depend on others, so all required types need to be installed when using the package.

[jjrv]

See microsoft/types-publisher#81

[ntindall]

I see. I was not aware that types-publisher advocates --save. We should close this as the root cause (scoped packages) is a known issue with npm-shrinkwrap.