Remove some `unpopular` detection (#2255)

* Remove some `unpopular` detection

Those have zero hits on https://www.wappalyzer.com/technologies

* Remove icons

src/apps.json

@@ -2379,16 +2379,6 @@
       "script": "dataTables.*\\.js",
       "website": "http://datatables.net"
     },
-    "David Webbox": {
-      "cats": [
-        22
-      ],
-      "headers": {
-        "Server": "David-WebBox/([\\d.a]+ \\(\\d+\\))\\;version:\\1"
-      },
-      "icon": "David Webbox.png",
-      "website": "http://www.tobit.com"
-    },
     "Debian": {
       "cats": [
         28
@@ -2806,27 +2796,6 @@
       },
       "website": "http://www.eprints.org"
     },
-    "ESERV-10": {
-      "cats": [
-        22
-      ],
-      "headers": {
-        "Server": "ESERV-10(?:/([\\d.]+))?\\;version:\\1"
-      },
-      "icon": "ESERV-10.png",
-      "website": "http://www.violasystems.com"
-    },
-    "EWS-NIC4": {
-      "cats": [
-        22
-      ],
-      "headers": {
-        "Server": "EWS-NIC4(?:\\/([\\d\\.a-z]+))?\\;version:\\1"
-      },
-      "icon": "EWS-NIC4.png",
-      "implies": "Dell",
-      "website": "http://dell.com"
-    },
     "EdgeCast": {
       "cats": [
         31
@@ -2969,16 +2938,6 @@
       ],
       "website": "https://etherpad.org"
     },
-    "Exagon Concept": {
-      "cats": [
-        1
-      ],
-      "headers": {
-        "Server": "Exagon Server"
-      },
-      "icon": "ExagonConcept.svg",
-      "website": "http://www.exagon-concept.com"
-    },
     "Exhibit": {
       "cats": [
         25

src/icons/ExagonConcept.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64"><path fill="#3DA8CC" d="M28.012 27.998H.004v8h28.008v-8zm3.988-20H.004v8h32.01l-.014-8zm20.02 0H40.016L51.309 30.31 40.016 47.998H.004L0 56.002h48.879L64 30.311 52.02 7.998z"/></svg>