Prepare for rollup-1.0

[lukastaegert]

Besides updating all dependenices, this introduces some fundamental changes, many of which are inspired by other PRs:

• Minimum TypeScript version is 2.1; version 3 is supported as well
• Instead of custom helpers, use tslib for TypeScript helpers
• Both TypeScript and tslib become peer dependencies
• Injecting a custom tslib is possible as well
• If the tsconfig option is a path, this path will be used to find a tsconfig file
• Support for dynamic imports
• Support for CommonJS imports if configured correctly, cf. README
• Fix an issue when no tsconfig.json file is present.
• Tests will work with Rollup@1.0
• Tests will run on node 7 again
• Updated readme

closes #117
closes #104 (I believe the use of tslib makes this unnecessary)
closes #93
resolves #123
resolves #122
resolves #114
resolves #113
resolves #112
resolves #111
resolves #110
resolves #96
resolves #94
resolves #80
resolves #27

[lukastaegert]

Feedback is of course welcome.
@Rich-Harris @TrySound @Victorystick @PaulBGD if one of you would grant me publishing rights to rollup-plugin-typescript, I can take care of releasing a new version.

[TrySound]

@lukastaegert Done

[lukastaegert]

Thanks!

[DanielRuf]

Node.js 7 and other odd releases are short instable ones and already reached their EOL. So it does not make much sense to use them. People use 6, 8 and 10 as 6 was the previous LTS branch.