Refactor

As all points from the epic refactor issue are closed #47 (closed) I am merging this in to master in order to unblock development.

backend/core/fixtures/testdata-core.json

-[
-    {
-        "fields": {
-            "full_score": 10,
-            "name": "Aufgabe 01",
-            "solution": "solution",
-            "slug": "brezmaphgocfuikw",
-            "description": "description"
-        },
-        "model": "core.submissiontype",
-        "pk": 1
-    },
-    {
-        "fields": {
-            "full_score": 20,
-            "name": "Aufgabe 02",
-            "solution": "solution",
-            "slug": "zbjfwldsuhqgxvmn",
-            "description": "description"
-        },
-        "model": "core.submissiontype",
-        "pk": 2
-    },
-    {
-        "fields": {
-            "has_logged_in": false,
-            "matrikel_no": "12345678",
-            "name": "Student 01 Vorname und Nachname",
-            "user": 4
-        },
-        "model": "core.student",
-        "pk": 1
-    },
-    {
-        "fields": {
-            "has_logged_in": false,
-            "matrikel_no": "87654321",
-            "name": "Student 02 Vorname und Nachname",
-            "user": 5
-        },
-        "model": "core.student",
-        "pk": 2
-    },
-    {
-        "fields": {
-            "seen_by_student": false,
-            "slug": "qgleatcwzfxsdnjr",
-            "student": 1,
-            "text": "function generate(timeout){\r\n\r\n\t$('#menu_button_img').attr('src', 'style/menu_blink.gif'); \r\n\r\n\tif(timeout == 0)\t\t\t\t\t\t\t\t\r\n\t\t$('#config_form').attr('action', $('#config_form').attr('action') + '#title'); \t\t\t\t// show directly the question\r\n\telse\r\n\t\ttimeout = 0;\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t// disable timeout\r\n\t\r\n\tsetTimeout(function(){ $('#config_form').submit(); }, timeout);\r\n\r\n}",
-            "type": 1
-        },
-        "model": "core.submission",
-        "pk": 1
-    },
-    {
-        "fields": {
-            "seen_by_student": false,
-            "slug": "mrthqgsloaydjfnc",
-            "student": 1,
-            "text": "function showTextEditor(){\r\n\r\n\t$('.ilc_question_Standard').hide('slow');\r\n\t$('.ilc_question_ml_Standard').hide('slow');\r\n\t$('.text_editor').show('slow');\r\n\t\r\n}\r\n\r\nfunction showConfig(){\r\n\r\n\t$('#config_wrapper').animate(\r\n\t\t{\r\n\t\t\tright: ($('#config_wrapper').css('right') == '0px' ? '-322px' : '0px')\r\n\t\t}, \r\n\t500);\r\n\r\n}",
-            "type": 2
-        },
-        "model": "core.submission",
-        "pk": 2
-    },
-    {
-        "fields": {
-            "seen_by_student": false,
-            "slug": "hunkgevtcfdobyxw",
-            "student": 2,
-            "text": "$(document).keydown(function(evt){\r\n\r\n\tif(evt.which == 9){\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t// #9 = TAB\r\n\t\tgenerate(0);\r\n\t\tevt.preventDefault();\r\n\t}\r\n\t\r\n});",
-            "type": 2
-        },
-        "model": "core.submission",
-        "pk": 3
-    },
-    {
-        "fields": {
-            "seen_by_student": false,
-            "slug": "gurvbyzxjfmhdiep",
-            "student": 2,
-            "text": "function showTextEditor(){\r\n\r\n\t$('.ilc_question_Standard').hide('slow');\r\n\t$('.ilc_question_ml_Standard').hide('slow');\r\n\t$('.text_editor').show('slow');\r\n\t\r\n}\r\n\r\nfunction showConfig(){\r\n\r\n\t$('#config_wrapper').animate(\r\n\t\t{\r\n\t\t\tright: ($('#config_wrapper').css('right') == '0px' ? '-322px' : '0px')\r\n\t\t}, \r\n\t500);\r\n\r\n}",
-            "type": 1
-        },
-        "model": "core.submission",
-        "pk": 4
-    }
-]