Add environment configuration for default page routing

jambotron-ui/src/environments/environment.development.ts

@@ -0,0 +1,3 @@
+export const environment = {
+  default_page: 'main/generate-image'
+};

jambotron-ui/src/environments/environment.ts

@@ -0,0 +1,3 @@
+export const environment = {
+  default_page: 'main/generate-image'
+};