Activating source-map-support several times leads to issues

I've just encountered the fact that Protractor tests in TypeScript run via ts-node leads to broken stack traces, as both Protractor and ts-node call `require('source-map-support').install()` by default. See [this issue at ts-node](https://github.com/TypeStrong/ts-node/issues/268#issuecomment-357518717) and [this example repo](https://github.com/renehamburger/ts-node-stack-problem).

In this case, the solution is simple, as Protactor allows to switch off source map support, but it would be worth to either investigate this bug or log an error message to notify the user that souce-map-support was activated twice.