Updated the Makefile

* It now downloads dependencies: jsdoc-toolkit, yuicompressor and the stuff needed for the unit tests
* dist.js is now automatically minified
* The test*.html files are automatically generated and will include all unit tests. Furthermore, there are two versions now: one which runs the tests on the development files and the other one on dist.js
Merge branch 'tests' of github.com:sara-nl/js-webdav-client into tests
Fixed a Makefile bug and changed test filenames so they are run in a certain order