update default values

cookiecutter.json

 {
-    "database_name": "Database Name",
+    "database_name": "Database_Name",
     "database_slug": "{{ cookiecutter.database_name.lower().replace(' ', '_') }}",
-    "package_name": "DAL {{ cookiecutter.database_name }}",
+    "package_name": "DAL_{{ cookiecutter.database_name }}",
     "package_slug": "{{ cookiecutter.package_name.lower().replace(' ', '_') }}",
     "package_version": "0.1.0",
     "author_fullname": "Author Fullname",