Upgrade Rollup to ^0.58.2

[laurentgoudet]

This upgrades Rollup to ^0.58.2 in order to fix https://github.com/jspm/jspm-cli/issues/2405:

• moduleName has been renamed to name, not mentioned in the changelog but it complains otherwise (and moduleName isn't in https://rollupjs.org/guide/en#big-list-of-options)
• bundle.generate now returns a Promise as per https://github.com/rollup/rollup/blob/master/CHANGELOG.md#0450
• es6 module format has been renamed es (deprecated in https://github.com/rollup/rollup/blob/master/CHANGELOG.md#0320)
• format doesn't default to es anymore (see https://github.com/rollup/rollup/pull/1491#issuecomment-321714821)

npm test runs without errors & I've successfully tested jspm build with different output formats in some small projects. This might break existing code relying on Rollup previous buggy behaviors that have now been fixed.

[guybedford]

Great work, thanks so much for the PR.