data: added overview page with flexible listview grid

data/job_posting_overview.json

+{
+  "portal_type_source": "Job Posting",
+  "portal_type_title": "job_posting",
+  "initial_query": {"include_docs": true, "limit": [0,8], "select_list": ["_id", "job_title", "job_location", "job_poster_subordinate_company_title", "job_post_logo_subordinate_logo_url", "date_posted"] },
+  "property_dict": {
+    "link": "true",
+    "link_identifier": "_id",
+    "search": {
+      "text": "Search Job Postings",
+      "text_i18n": "portal_type_dict.job_posting_dict.text_dict.search",
+      "info_list": ["records"],
+      "class_list": "responsive"
+    },
+    "pagination": {
+      "class_list": "center",
+       "option_list": [
+         {"value": "8", "text": "8", "text_i18n":"global_dict.8"},
+         {"value": "16", "text": "16", "text_i18n":"global_dict.16"},
+         {"value": "32", "text": "32", "text_i18n":"global_dict.32"},
+         {"value": "64", "text": "64", "text_i18n":"global_dict.64"}
+       ]
+     }
+  },
+  "scheme": [
+    {
+      "position": "left",
+      "field_list": [
+        {"field": "job_post_logo_subordinate_logo_url", "type":"image"}
+      ]
+    }, {
+      "position": "center",
+      "field_list": [
+        {"field": "job_title", "type": "h3"},
+        {"field": "job_poster_subordinate_company_title", "type": "p", "mergeText": "job_location"},
+        {"field": "job_location", "type": "p"},
+        {"field": "date_posted", "aside": true}
+      ]
+    }
+  ],
+  "children": [{
+    "generate": "widget",
+    "type": "listview",
+    "property_dict": {
+      "class_list": "responsive ui-image-grid",
+      "theme": "slapos-white",
+      "map_children": "listItem",
+      "dynamic": true
+    },
+    "children":[]
+  }]
+}
+