Add routing and pages for managing templates

So that users can see what it the flow is like to:
- add new templates
- edit existing templates

app/main/views/templates.py

@@ -0,0 +1,32 @@
+from flask import request, render_template, redirect, url_for
+
+from app.main import main
+
+
+@main.route("/templates")
+def manage_templates():
+    return render_template('views/manage-templates.html')
+
+
+@main.route("/templates/template", methods=['GET', 'POST'])
+def add_template():
+    if request.method == 'GET':
+        return render_template(
+            'views/edit-template.html',
+            template_name='Reminder',
+            template_body='Vehicle tax: Your vehicle tax for ((registration number)) expires on ((date)). Tax your vehicle at www.gov.uk/vehicle-tax',  # noqa
+            h1='Edit template'
+        )
+    elif request.method == 'POST':
+        return redirect(url_for('.manage_templates'))
+
+
+@main.route("/templates/template/add", methods=['GET', 'POST'])
+def edit_template():
+    if request.method == 'GET':
+        return render_template(
+            'views/edit-template.html',
+            h1='Add template'
+        )
+    elif request.method == 'POST':
+        return redirect(url_for('.manage_templates'))