Config, secrets, basic POST handling

* add script/config
  * add atst.ini
  * add cookie_secret
  * update docs

script/config

@@ -0,0 +1,3 @@
+cp atst.ini.example atst.ini
+rand=`head -c 400 /dev/random | tr -dc A-Za-z0-9_=,@-`
+perl -p -i -e "s/change_me_into_something_secret/$rand/" atst.ini

script/setup

@@ -24,5 +24,8 @@ fi
 # Install application dependencies
 script/bootstrap
 
+# Generate default configuration
+script/config
+
 # Symlink uswds fonts into the /static directory
 ln -s ../node_modules/uswds/src/fonts ./static/fonts