Response improvements, some tests, and deployment script

It’s been a long time since I made a pull request. This one is huge, and I’m sorry for that. It’s basically all that I’ve been working on, regarding some important topics for Bottle.

I first enhanced the Response object. We can now send custom headers, and use some utility functions, such as redirect(). More utilities functions, such as an `@ajax` decorat^wannotation, will come soon.

I also started to write tests. Only some functionnal tests are written now, because I spent most of the time building the test environment: a web server is spawned in background with the tests in order to run the Bottle application in a real-world way. It’s related with issue #2 .

Finally, I wrote a script to make a PHAR archive from the entire Bottle framework. I think it’s more efficient than trying to pack PHP code in a single file, and also much easier to deploy. I moved the Bottle sources to the `src` dir to make the archive work easier. I also made a new branch, `deployment`, which will contain only the phar file, for easy deployments with git.

My next move will be focused on documentation, testing and stability.
Some wrapper would be preferable here too