Feature/tests

I started working on automated testing a while back. This is of course not finished, yet, but I consider it in a quite useful state. I updated the readme file to show how development could be done.

What this brings is:

* a few helpers for firefox (I consider this minor, but might make some ff-devs more happy)
* a static webserver
* a static web-page with
    * a key (public + private part) to import
    * an encrypted text (decrypt it with the key mentioned above)
    * a textarea to test signing and encryption
    * a signed message for an unknown key
    * a signed message with the key mentioned above

Together with the already available `watch` task, this is quite a nice tool for development. I played around a little with live-reloading, but I couldn’t find a way to reload the chrome extension. So I left this out, for now. For future development I plan to add this and implement some nice automated test stack that does all the boring stuff for you. (Testing all possible combinations of encryption, signing, with external editor and all the things you forget testing during your normal development process.)

But for now it would be great to have this merged, so I don’t need to rebase as often, as I do at the moment (I’ve been using this branch for development and it seems to work nicely)