Feature/user experience

Acceptance criteria

[ ] The character counter is shown at the description form field on the addTrip page and edit trip page
[ ] The wording of the CTAs gives clear advice how to act as a user
[ ] The back-link on the addTrip page redirects to the overview page without any additional message
[ ] Clicking on the edit trip button saves the current values of each form field to the trip and sends the user to the updated detailspage of given trip
[ ] The input values of the date form fields are displayed when editing a trip
[ ] The tripList is chronologically ordered based on the start date