diesel db handling

* update settings for test environment (.env)
* migrations subdir with sql prototypes

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

diesel.toml

@@ -2,4 +2,5 @@
 # see diesel.rs/guides/configuring-diesel-cli
 
 [print_schema]
-file = "src/schema.rs"
+file = "src/db/schema.rs"
+#filter = { only_tables = [ "User", "UserRole" ] }