Added key-value like db table for config flags

ref #110

src/models/entities/ConfigFlags.ts

@@ -0,0 +1,27 @@
+import {
+    IsNotEmpty,
+    IsString
+} from "class-validator";
+import { Column, Entity, PrimaryColumn } from "typeorm";
+
+/**
+ * Defines the ConfigFlag entity.
+ * This entity can be used to set some flags on db init.
+*/
+@Entity()
+export class ConfigFlag {
+    /**
+     * The flag's name (primary).
+     */
+    @PrimaryColumn()
+    @IsString()
+    option: string;
+
+    /**
+     * The flag's value.
+     */
+    @Column()
+    @IsString()
+    @IsNotEmpty()
+    value: string;
+}