https://github.com/tracim/tracim/issues/748, translation of login and dashboard page

frontend/i18next.scanner/en/translation.json

   "Old password": "Old password",
   "New password": "New password",
   "Name:": "Name:",
-  "Email Adress:": "Email Adress:"
+  "Email Adress:": "Email Adress:",
+  "An error has happened": "An error has happened",
+  "You have subscribed to this workspace's notifications": "You have subscribed to this workspace's notifications",
+  "Connection": "Connection",
+  "Forgotten password ?": "Forgotten password ?",
+  "currently, you are ": "currently, you are "
 }

frontend/i18next.scanner/fr/translation.json

   "Old password": "Ancien mot de passe",
   "New password": "Nouveau mot de passe",
   "Name:": "Nom :",
-  "Email Adress:": "Adresse mail :"
+  "Email Adress:": "Adresse mail :",
+  "An error has happened": "__NOT_TRANSLATED__",
+  "You have subscribed to this workspace's notifications": "Vous êtes abonné aux notifications de cet espace de travail.",
+  "Connection": "Connexion",
+  "Forgotten password ?": "Mot de passe oublié ?",
+  "currently, you are ": "actuellement, vous êtes "
 }

frontend/src/container/Dashboard.jsx

               <div className='dashboard__userstatut'>
                 <div className='dashboard__userstatut__role'>
                   <div className='dashboard__userstatut__role__msg'>
-                    {props.t(`Hi ! ${props.user.public_name}, vous êtes actuellement`)}
+                    {props.t(`Hi ! ${props.user.public_name} `)}{props.t('currently, you are ')}
                   </div>
 
                   <div className='dashboard__userstatut__role__definition'>
                           aria-haspopup='true'
                           aria-expanded='false'
                         >
-                          Abonné(e)
+                          {props.t('subscriber')}
                         </button>
 
                         <div className='dashboard__userstatut__notification__subscribe__submenu dropdown-menu'>

frontend/src/container/Login.jsx

               <div className='col-12 col-sm-11 col-md-8 col-lg-6 col-xl-4'>
 
                 <Card customClass='loginpage__connection'>
-                  <CardHeader customClass='connection__header text-center'>{'Connexion'}</CardHeader>
+                  <CardHeader customClass='connection__header text-center'>{this.props.t('Connection')}</CardHeader>
 
                   <CardBody formClass='connection__form'>
                     <div>
                         <div className='col-12 col-sm-6 col-md-6 col-lg-6 col-xl-6 text-sm-right'>
                           <LoginBtnForgotPw
                             customClass='connection__form__pwforgot'
-                            label='Mot de passe oublié ?'
+                            label={this.props.t('Forgotten password ?')}
                           />
                         </div>
                       </div>
                         htmlType='button'
                         bootstrapType='primary'
                         customClass='connection__form__btnsubmit ml-auto'
-                        label='Connexion'
+                        label={this.props.t('Connection')}
                         onClick={this.handleClickSubmit}
                       />
                     </div>