func (cmt *contractManagerTester) panicClose() {
	err := cmt.Close()
	if err != nil {
		panic(err)
	}
}
panicClose will attempt to call Close on the contract manager tester. If
there is an error, the function will panic. A convenient function for making
sure that the cleanup code is always running correctly, without needing to
write a lot of boiler code.
package contractmanager
import (
	"errors"
	"os"
	"path/filepath"
	"testing"
	"github.com/NebulousLabs/Sia/build"
	"github.com/NebulousLabs/Sia/modules"
)
type contractManagerTester struct {
	cm *ContractManager
	persistDir string
}