Fixed bad Tests directory tree

See:

- http://stackoverflow.com/a/15466251/2016221
- guzzle architecture
Extracted FileSystemTestHelper
Moved file scanning to FileSystem; added tests
Added CheckRepository; made existing checks work

This commit breaks hippo because it makes existing untested Check
implementations work.
Removed unneeded objects
Added config to checks; disabled all checks
Improved informativeness of config exceptions
Fixed Check contract

Checks apparently didn't return CheckResult at all. Now, instead of
adding "return $checkResult" to every check and ensuring the
$checkResult is reset right after starting checkFile(), I decided it's
more convenient to wrap this in AbstractCheck since it already contains
similar logic.
Fixed Check not being given File it's intended for
Enabled max line length check
Fixed and refactored max line length check
Moved stuff to CheckRunner
Added additional newline to CLI report
Fixed line numbers being off by 1