241 modify bstat

Closes #249

fda-analyse-service/as-yml/bstatistic.yml

+summary: "Add basic statistics, i.e., determine  min, max, values of numerical columns..., and save to metadatabase"
+description: "Updates entity mdb_columns and mdb_columns_num (columns with numerical values), mdb_columns_nom (columns 
+nominal values) and mdb_columns_cat (columns with categorical values, e.g. ENUM datatypes) in metadatabase"
+consumes:
+- "application/json"
+produces:
+- "application/json"
+parameters:
+- in: "body"
+  name: "body"
+  description: "Updates entity mdb_columns, mdb_columns_nom (attribute max_length), mdb_columns_num (min, max, mean, sd, histogram) and mdb_columns_cat (num_cat, cat_array). The attribute 'histogram' describes a equi-width histogram with a fix number of 10 buckets. The last value in this numeric array is the width of one bucket. The attribute cat_array contains an array with the names of the categories."
+  required: true
+  schema:
+    type: "object"
+    properties:
+      dbid:
+        type: "integer"
+        example: 1
+      tid: 
+        type: "integer"
+        example: 1
+responses:
+  200:
+    description: "OK"
+  405:
+    description: "Invalid input"
+  409:
+    description: "Conflict"
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