rename public-api to api

we don't use the public-api bit anywhere - even cloudwatch overwrites
based on CW_APP_NAME (which we can get rid of as this distinction is
gone)

scripts/paas_app_wrapper.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 case $NOTIFY_APP_NAME in
-  public-api)
+  api)
     unset GUNICORN_CMD_ARGS
     scripts/run_app_paas.sh gunicorn -c /home/vcap/app/gunicorn_config.py application
     ;;