Mute warnings.

If the cached file does not yet exist, PHP (depending on error_level) will throw an annoying warning in the error log.
Add a robots.txt

Presumably there's nothing to be crawled anyways.
Add .gitignore

Ignore the contents of the cache/ folder.
Merge pull request #4 from brycied00d/add_robots

Add a robots.txt
Merge pull request #7 from brycied00d/add_gitignore

Add .gitignore
Merge pull request #6 from brycied00d/mute_php_file_warnings

Mute warnings.