As discussed in #552 (comment) for consistency reason we should use - or _ for all the directory names. The only exception at the moment is index-template. Instead it should be called index_template.

To support this change, not changes in the package-registry are needed but Kibana and packages need to be updated. The suggested path forward is:

• Update all packages with index_template but also keep index-template as a duplicate around Update base packages to use new paths package-storage#90
• Switch Kibana over to index_template, ilm_policy, component_template
• Remove all index-template directory in packages.