(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/gen-server/migration/1549381727494-UserPicture.ts

@@ -0,0 +1,16 @@
+import {MigrationInterface, QueryRunner, TableColumn} from "typeorm";
+
+export class UserPicture1549381727494 implements MigrationInterface {
+
+    public async up(queryRunner: QueryRunner): Promise<any> {
+      await queryRunner.addColumn("users", new TableColumn({
+        name: "picture",
+        type: "varchar",
+        isNullable: true,
+      }));
+    }
+
+    public async down(queryRunner: QueryRunner): Promise<any> {
+      await queryRunner.dropColumn("users", "picture");
+    }
+}