Make testing more flexible

- new testing content dir name (easier to understand what it does)
- test.dir reacts on changes to content dir name
- move site() call to blueprint, because you simply need it everywhere and it failed for some tests when directly called
Fix wrong path in comment
Merge branch 'master' of https://github.com/kirbycms/core

Conflicts:
	tests/bootstrap.php
	tests/index.php
Add support for PHPUnit

This also adds some fixes (wrong tests that were passing but are actually failing).

Please fix everything that is in the error list in the moment!
Add Travis support (YAAY!)
Merge pull request #1 from vis7mac/testing

Some testing improvements