feat(observations): Display date instead of timestamp in list and detail view

observations/locale/bg/LC_MESSAGES/django.po

observations/locale/bg/LC_MESSAGES/djangojs.po

observations/locale/bs/LC_MESSAGES/django.po

observations/locale/bs/LC_MESSAGES/djangojs.po

observations/locale/de/LC_MESSAGES/django.po

observations/locale/de/LC_MESSAGES/djangojs.po

observations/locale/fi/LC_MESSAGES/django.po

observations/locale/fi/LC_MESSAGES/djangojs.po

observations/locale/nb/LC_MESSAGES/django.mo

observations/locale/nb/LC_MESSAGES/django.po

observations/locale/nb/LC_MESSAGES/djangojs.po

observations/locale/vi/LC_MESSAGES/django.po

observations/locale/vi/LC_MESSAGES/djangojs.po

observations/locale/zh_Hans/LC_MESSAGES/django.mo

observations/locale/zh_Hans/LC_MESSAGES/django.po

observations/locale/zh_Hans/LC_MESSAGES/djangojs.po

observations/static/observations/js/observationList.js

observations/templates/observations/detail.html

observations/templates/observations/index.html

observations/templates/observations/index_old.html