Database config page for when config is missing.

Fixes #244.

![image](https://cloud.githubusercontent.com/assets/1657047/3034525/97b069ae-e075-11e3-9448-c8752359808e.png)
![image](https://cloud.githubusercontent.com/assets/1657047/3034557/35032c8c-e076-11e3-8d46-90f5b27086c3.png)

Why does your character class need to include all characters except `(<)|(\?)`? It seems that the only line you need to exclude starts with either `<` in `<?php` or with `?` in `?>`. Furthermore, your character class excludes `(` twice. Perhaps use `[^<?]`. Remember that parentheses within `[]` do not group - they indicate literal characters within the character class mini-language.