Clean up the default config so it's more readable.

Move the truncate option from the class.krumo.php in to the config.
Why was there a "config" option set as a constant anyway? It makes
a lot more sense in the config.
Fix readable -> is_readable
Some cleanup since we don't support PHP 4.x anymore
Move the logic default of /krumo/ for the CSS path out of
the get_relative_path() function. This makes get_relative_path()
agnositc to Krumo.
Remove another PHP 4.x.x check as we don't support PHP 4.
There are no more references to PHP 4.x in the code.
Update the README.md documentation

Include information about how to include Krumo "raw".
Merge pull request #5 from scottchiefbaker/master

Clean up the default config so it's more readable.