authenticate/proxy: add user impersonation, refresh, dashboard (#123)

proxy: Add user dashboard. [GH-123]
proxy/authenticate: Add manual refresh of their session. [GH-73]
authorize: Add administrator (super user) account support. [GH-110]
internal/policy: Allow administrators to impersonate other users. [GH-110]

internal/cryptutil/mock_cipher.go

@@ -0,0 +1,28 @@
+package cryptutil // import "github.com/pomerium/pomerium/internal/cryptutil"
+
+// MockCipher MockCSRFStore is a mock implementation of Cipher.
+type MockCipher struct {
+	EncryptResponse []byte
+	EncryptError    error
+	DecryptResponse []byte
+	DecryptError    error
+	MarshalResponse string
+	MarshalError    error
+	UnmarshalError  error
+}
+
+// Encrypt is a mock implementation of MockCipher.
+func (mc MockCipher) Encrypt(b []byte) ([]byte, error) { return mc.EncryptResponse, mc.EncryptError }
+
+// Decrypt is a mock implementation of MockCipher.
+func (mc MockCipher) Decrypt(b []byte) ([]byte, error) { return mc.DecryptResponse, mc.DecryptError }
+
+// Marshal is a mock implementation of MockCipher.
+func (mc MockCipher) Marshal(i interface{}) (string, error) {
+	return mc.MarshalResponse, mc.MarshalError
+}
+
+// Unmarshal is a mock implementation of MockCipher.
+func (mc MockCipher) Unmarshal(s string, i interface{}) error {
+	return mc.UnmarshalError
+}