Added issue search via api (#3612)

* Started implementing issue api search

* Implemented issue search via api

* Added search to swagger.json

* Removed todo

* fmt

* Added comment to generate swagger json via "generate-swagger"

* Simplified search

* fmt

* Removed unessecary comment

* Removed unessecary declaration of the issues-variable

* Removed unessecary comment

* Removed unessecary comment

* Added explanation keyword

* Simplified check for empty keyword

* corrected check if keyword is empty

public/swagger.v1.json

@@ -1830,6 +1830,12 @@
             "description": "page number of requested issues",
             "name": "page",
             "in": "query"
+          },
+          {
+            "type": "string",
+            "description": "search string",
+            "name": "q",
+            "in": "query"
           }
         ],
         "responses": {