fix airgapped test, func rename, update HowTo.md

HowTo.md

@@ -88,7 +88,7 @@ Start the airgapped machine:
 # First print your node's address; you will be prompted to enter it.
 $ ./dc4bc_cli get_address --listen_addr localhost:8080
 e0d8083f8a2d18f310bfbdc9649a83664470f46053ab53c105a054b08f9eff85
-$ ./dc4bc_airgapped /tmp/dc4bc_john_doe_airgapped_state
+$ ./dc4bc_airgapped --db_path /tmp/dc4bc_john_doe_airgapped_state --password_expiration 10m
 ```
 Print your address, communication public key and encryption public key and save it somewhere for later use:
 ``` 

airgapped/airgapped_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"os"
 	"sync"
 	"testing"
 	"time"
@@ -101,6 +102,7 @@ func createOperation(t *testing.T, opType string, to string, req interface{}) cl
 }
 
 func TestAirgappedAllSteps(t *testing.T) {
+	testDir := "/tmp/airgapped_test"
 	nodesCount := 10
 	threshold := 3
 	participants := make([]string, nodesCount)
@@ -110,7 +112,7 @@ func TestAirgappedAllSteps(t *testing.T) {
 
 	tr := &Transport{}
 	for i := 0; i < nodesCount; i++ {
-		am, err := NewAirgappedMachine(fmt.Sprintf(testDB+"%d", i))
+		am, err := NewAirgappedMachine(fmt.Sprintf("%s/%s-%d", testDir, testDB, i))
 		if err != nil {
 			t.Fatalf("failed to create airgapped machine: %v", err)
 		}
@@ -126,6 +128,7 @@ func TestAirgappedAllSteps(t *testing.T) {
 		}
 		tr.nodes = append(tr.nodes, &node)
 	}
+	defer os.RemoveAll(testDir)
 
 	var initReq responses.SignatureProposalParticipantInvitationsResponse
 	for _, n := range tr.nodes {

cmd/airgapped/main.go

@@ -191,7 +191,7 @@ func (t *terminal) run() error {
 	}
 }
 
-func (t *terminal) sensitiveDataDrop(passExpiration time.Duration) {
+func (t *terminal) dropSensitiveData(passExpiration time.Duration) {
 	ticker := time.NewTicker(passExpiration)
 	for {
 		select {
@@ -225,7 +225,7 @@ func main() {
 	}
 
 	t := NewTerminal(air)
-	go t.sensitiveDataDrop(passwordLifeDuration)
+	go t.dropSensitiveData(passwordLifeDuration)
 	if err = t.run(); err != nil {
 		log.Fatalf(err.Error())
 	}