TUN-4063: Cleanup dependencies between packages.

- Move packages the provide generic functionality (such as config) from `cmd` subtree to top level.
- Remove all dependencies on `cmd` subtree from top level packages.
- Consolidate all code dealing with token generation and transfer to a single cohesive package.

config/configuration_test.go

@@ -0,0 +1,83 @@
+package config
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/yaml.v2"
+)
+
+func TestConfigFileSettings(t *testing.T) {
+	var (
+		firstIngress = UnvalidatedIngressRule{
+			Hostname: "tunnel1.example.com",
+			Path:     "/id",
+			Service:  "https://localhost:8000",
+		}
+		secondIngress = UnvalidatedIngressRule{
+			Hostname: "*",
+			Path:     "",
+			Service:  "https://localhost:8001",
+		}
+		warpRouting = WarpRoutingConfig{
+			Enabled: true,
+		}
+	)
+	rawYAML := `
+tunnel: config-file-test
+ingress:
+ - hostname: tunnel1.example.com
+   path: /id
+   service: https://localhost:8000
+ - hostname: "*"
+   service: https://localhost:8001
+warp-routing: 
+  enabled: true
+retries: 5
+grace-period: 30s
+percentage: 3.14
+hostname: example.com
+tag:
+ - test
+ - central-1
+counters:
+ - 123
+ - 456
+`
+	var config configFileSettings
+	err := yaml.Unmarshal([]byte(rawYAML), &config)
+	assert.NoError(t, err)
+
+	assert.Equal(t, "config-file-test", config.TunnelID)
+	assert.Equal(t, firstIngress, config.Ingress[0])
+	assert.Equal(t, secondIngress, config.Ingress[1])
+	assert.Equal(t, warpRouting, config.WarpRouting)
+
+	retries, err := config.Int("retries")
+	assert.NoError(t, err)
+	assert.Equal(t, 5, retries)
+
+	gracePeriod, err := config.Duration("grace-period")
+	assert.NoError(t, err)
+	assert.Equal(t, time.Second*30, gracePeriod)
+
+	percentage, err := config.Float64("percentage")
+	assert.NoError(t, err)
+	assert.Equal(t, 3.14, percentage)
+
+	hostname, err := config.String("hostname")
+	assert.NoError(t, err)
+	assert.Equal(t, "example.com", hostname)
+
+	tags, err := config.StringSlice("tag")
+	assert.NoError(t, err)
+	assert.Equal(t, "test", tags[0])
+	assert.Equal(t, "central-1", tags[1])
+
+	counters, err := config.IntSlice("counters")
+	assert.NoError(t, err)
+	assert.Equal(t, 123, counters[0])
+	assert.Equal(t, 456, counters[1])
+
+}