Add remaining strings for vector-im/riot-web#4151

src/components/structures/MatrixChat.js

@@ -684,8 +684,13 @@ module.exports = React.createClass({
 
         const roomToLeave = MatrixClientPeg.get().getRoom(roomId);
         Modal.createDialog(QuestionDialog, {
-            title: "Leave room",
-            description: <span>Are you sure you want to leave the room <i>{roomToLeave.name}</i>?</span>,
+            title: _t("Leave room"),
+            description: (
+                <span>
+                {_t("Are you sure you want to leave the room ")}
+                <i>{roomToLeave.name}</i>?
+                </span>
+            ),
             onFinished: (shouldLeave) => {
                 if (shouldLeave) {
                     const d = MatrixClientPeg.get().leave(roomId);

src/components/structures/UserSettings.js

@@ -715,8 +715,8 @@ module.exports = React.createClass({
                 <h3>{ _t("Cryptography") }</h3>
                 <div className="mx_UserSettings_section mx_UserSettings_cryptoSection">
                     <ul>
-                        <li><label>Device ID:</label>             <span><code>{deviceId}</code></span></li>
-                        <li><label>Device key:</label>            <span><code><b>{identityKey}</b></code></span></li>
+                        <li><label>{_t("Device ID:")}</label>             <span><code>{deviceId}</code></span></li>
+                        <li><label>{_t("Device key:")}</label>            <span><code><b>{identityKey}</b></code></span></li>
                     </ul>
                     { importExportButtons }
                 </div>

src/components/structures/login/ForgotPassword.js

@@ -229,7 +229,7 @@ module.exports = React.createClass({
                     <div className="mx_Login_error">
                     </div>
                     <a className="mx_Login_create" onClick={this.props.onLoginClick} href="#">
-                        Return to login
+                        {_t('Return to login screen')}
                     </a>
                     <a className="mx_Login_create" onClick={this.props.onRegisterClick} href="#">
                         { _t('Create an account') }