Access to Memory (AtoM)

An issue was reported where if urls were constructed with bad sf_culture
values and bad sf_cache_config values, cache files with the same
names/paths would be created in the partials cache directory structure.

This was happening because the sf_culture value was merely checked to
see if it was not null, and if so, it was assigned to the session culture
value. Once this happens, this sf_culture value gets used as sf_cache_key for
partial views. A cache file will not be found named with the garbage value and
so the view cache manager will create a new corresponding cache file.

I have added code to filter bad sf_culture values. I have changed the
check in sfUser.class.php to instead verify that it is a valid
sf_culture, and if not, fall back to:

- use the culture defined in the user session
- use the default culture set in settings.yml

This prevents 500 errors and prevents the ability to inject paths and
files into the cache directory.

To replicate the bug, url must be formed such that sf_cache_config and sf_culture are both included.

sf_cache_config must be set to a junk value
sf_culture must be set to a non valid language code

If both cases are true, files named identically to the lang code will be created in the cache dir.

e.g. 10.10.10.10?sf_cache_config=test&sf_culture=steve

The above will create a cache file called steve in the cache folder.