Fixes broken model tests by reverting changes made to command in #459

#### Summary:

Fixes running of models.

#### Intended Effect:

Before: running the Wishart test would run out of memory.
After: runs and quits, like v2.1.0.


#### How to Verify:

One example is:
`make test/CmdStan/models/basic_distributions/wishart`

#### Side Effects:

Lots of models should be broken now. This was introduced in #459 and I'm just reverting the changes in command.hpp.

#### Documentation:

None.

#### Reviewer Suggestions:

Michael.