Rakefile: wrap in bundle exec

[olleolleolle]

• I am trying to make the Travis build run license_finder

[olleolleolle]

@maxmeyer Oh, my investigation was not final - and the license_finder still fails in Travis, trying to locate the right gems in the Gemfile.lock - https://travis-ci.org/cucumber/aruba/jobs/252143170#L340 is an example of that.

[maxmeyer]

There's another PR fixing a lot of issues from @mvz, #434.

[olleolleolle]

@maxmeyer Thanks for linking to that! It explains so much

[mvz]

This commit shouldn't be needed since AIUI, all bundle exec does is set some environment variables, and these will already be inherited from the outer level bundle exec rake.

[maxmeyer]

@mvz You're right, I think that was the reason, why I didn't add it. but it doesn't do any harm for those using rake directly, right?

[mvz]

No, I don't think it does any harm.