Local windows support:
- Add dos2unix task for config
- Run dos2unix on code only if it was deployed via remote copy
- Introduce FIX_LINE_ENDINGS env var to force dos2unix to run
- Refactor rubber:config task to have sub tasks :push and :configure, so we can hook dos2unix between the two steps.
- Remove use_dos2unix variable (which was introduced in early attempts at Windows support)
Detect alternate location of secret file when it is moved into the /config/rubber dir on remote servers.

If you named your sercet file as /secret/rubber-secret.yml, this would work by accident since it would be picked up by the `read_config method`, not the `read_secret_config method`