Expose options

[alkalinecoffee]

This PR exposes the minitest options var.

Our team leverages minitest with a custom library to make live HTTP requests against our APIs. Particularly, we want access to the generated seed value so we can easily identify specific test runs in logs/splunk (our API test library would pass this value along in each request during the test run).

[aiomaster]

LOL, just now I see this pull request that does very much the same like mine:
#657

Sorry @alkalinecoffee , that I had not seen this before.
It would be very cool if one of these two pull requests could get merged.

@zenspider: Should I close mine?
Only difference is, where exactly the options variable is set.

[zenspider]

I absolutely do NOT want options available to tests. Instead, I've exposed the seed being used via Minitest.seed.