add migration file for creating blockchain_project_clients table

db/migrate/20190725025825_create_blockchain_project_clients.rb

@@ -0,0 +1,12 @@
+class CreateBlockchainProjectClients < ActiveRecord::Migration
+  def change
+    create_table :blockchain_project_clients do |t|
+
+      t.references :project
+      t.references :user
+
+      t.string :node_id
+      t.timestamps
+    end
+  end
+end