ref https://github.com/marijnh/tern/issues/424 Creating tern repo.

tern metadata/repository.json from `*.metadata.json` files

Example of output file

```js
[
  {
    "name": "angular",
    "metadataurl": "https://raw.githubusercontent.com/angelozerr/tern.java/master/core/tern.core/metadata/angular.metadata.json"
  },
  {
    "name": "aui",
    "metadataurl": "https://raw.githubusercontent.com/angelozerr/tern.java/master/core/tern.core/metadata/aui.metadata.json"
  },

```