Dictionary Definition - Rename content template to content.handlebars

[moollaza]

The content template shouldn't be named after the spice. It should be called content.handlebars, and then should be referenced like so:

options: {
    content: Spice.dictionary_definition.content
}

[jagtalon]

Fixed by @killerfish in https://github.com/duckduckgo/zeroclickinfo-spice/pull/975