Use 'Sign In' / 'Sign Out' universally

Rather than a mix of 'sign in/out' and 'log in/out'

src/components/structures/MatrixChat.js

@@ -667,8 +667,8 @@ module.exports = React.createClass({
         cli.on('Session.logged_out', function(call) {
             var ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
             Modal.createDialog(ErrorDialog, {
-                title: "Logged Out",
-                description: "For security, this session has been logged out. Please log in again."
+                title: "Signed Out",
+                description: "For security, this session has been signed out. Please sign in again."
             });
             dis.dispatch({
                 action: 'logout'

src/components/structures/UserSettings.js

@@ -560,7 +560,7 @@ module.exports = React.createClass({
                 <div className="mx_UserSettings_section">
 
                     <div className="mx_UserSettings_logout mx_UserSettings_button" onClick={this.onLogoutClicked}>
-                        Log out
+                        Sign out
                     </div>
 
                     {accountJsx}

src/components/structures/login/ForgotPassword.js

@@ -147,7 +147,7 @@ module.exports = React.createClass({
                 <div>
                     <p>Your password has been reset.</p>
                     <p>You have been logged out of all devices and will no longer receive push notifications.
-                    To re-enable notifications, re-log in on each device.</p>
+                    To re-enable notifications, sign in again on each device.</p>
                     <input className="mx_Login_submit" type="button" onClick={this.props.onComplete}
                         value="Return to login screen" />
                 </div>
@@ -188,7 +188,7 @@ module.exports = React.createClass({
                         onIsUrlChanged={this.onIsUrlChanged}
                         delayTimeMs={0}/>
                     <div className="mx_Login_error">
-                    </div>                        
+                    </div>
                     <a className="mx_Login_create" onClick={this.props.onLoginClick} href="#">
                         Return to login
                     </a>

src/components/views/login/CustomServerDialog.js

@@ -27,7 +27,7 @@ module.exports = React.createClass({
                 </div>
                 <div className="mx_Dialog_content">
                     <span>
-                        You can use the custom server options to log into other Matrix
+                        You can use the custom server options to sign into other Matrix
                         servers by specifying a different Home server URL.
                         <br/>
                         This allows you to use this app with an existing Matrix account on

src/components/views/login/PasswordLogin.js

@@ -104,7 +104,7 @@ module.exports = React.createClass({displayName: 'PasswordLogin',
                     placeholder="Password" />
                 <br />
                 {forgotPasswordJsx}
-                <input className="mx_Login_submit" type="submit" value="Log in" />
+                <input className="mx_Login_submit" type="submit" value="Sign in" />
                 </form>
             </div>
         );