Security Changes

Hi,

I promised some more pull requests, didn't I? So here I go ;)

I don't really want you to pull it, just thing about it. I did some security related changes to the storage-lib.

I didn't feel good about having an unencrypted certificate (PEMs are unencrypted) somewhere in my codebase. When working with Heroku, or any other git-based-deployment for that matter, you'll end up putting a certificate with root access to your company wide drive, into your git repo.
This isn't really secure.

That's why I figured the key needs to be passed a string. One can decided if he loads it over an environment variable or a file.

If you agree, I could adds backwards compatibility and deprecation warnings.

cheers,
joe