Storage has now it's own package.

Remove global `sessions` map and use configured storage.
Add a `types` package so both `pwd` and `storage` can access without
circular dependencies.
Now the session is prepared when requested and not on load.

pwd/types/session.go

@@ -0,0 +1,55 @@
+package types
+
+import (
+	"sync"
+	"time"
+)
+
+type Session struct {
+	Id           string               `json:"id"`
+	Instances    map[string]*Instance `json:"instances"`
+	CreatedAt    time.Time            `json:"created_at"`
+	ExpiresAt    time.Time            `json:"expires_at"`
+	PwdIpAddress string               `json:"pwd_ip_address"`
+	Ready        bool                 `json:"ready"`
+	Stack        string               `json:"stack"`
+	StackName    string               `json:"stack_name"`
+	ImageName    string               `json:"image_name"`
+	Clients      []*Client            `json:"-"`
+	closingTimer *time.Timer          `json:"-"`
+	scheduled    bool                 `json:"-"`
+	ticker       *time.Ticker         `json:"-"`
+	rw           sync.Mutex           `json:"-"`
+	prepared     bool                 `json:"-"`
+}
+
+func (s *Session) Lock() {
+	s.rw.Lock()
+}
+
+func (s *Session) Unlock() {
+	s.rw.Unlock()
+}
+
+func (s *Session) StopTicker() {
+	if s.ticker != nil {
+		s.ticker.Stop()
+	}
+}
+func (s *Session) SetTicker(t *time.Ticker) {
+	s.ticker = t
+}
+func (s *Session) SetClosingTimer(t *time.Timer) {
+	s.closingTimer = t
+}
+func (s *Session) ClosingTimer() *time.Timer {
+	return s.closingTimer
+}
+
+func (s *Session) IsPrepared() bool {
+	return s.prepared
+}
+
+func (s *Session) SetPrepared() {
+	s.prepared = true
+}