Print arg config after random seed generation

#### Summary:

Resolves #1049 by displaying the argument configuration to screen only after randomly generating a new seed.

#### Intended Effect:

Changes what is printed to screen in CmdStan (other interfaces do not use this code) -- has no effect on the actual configuration or running.

#### How to Verify:

In CmdStan run any model without specifying a random seed and see that the output printed to screen is the randomly generated seed consistent with that saved in output.csv.

#### Side Effects:

None.

#### Documentation:

None.

#### Reviewer Suggestions:

Anyone.