X shows when running a backup

![screen shot 2014-11-20 at 17 49 52](https://cloud.githubusercontent.com/assets/308507/5129827/b45427dc-70dd-11e4-9204-950356e48fc6.png)

Steps to reproduce:

1. Click run backup
2. Don't reload the page
3. Wait for the backup to complete
4. Notice there is a cross instead of a tick
I know both ways are valid, both ways are also used in Core (although with parenthesis is far more common)

- 267 instances of `require_once(` vs 48 instance of `require_once `
- 160 instance of `require(` vs 75 instance of `require `

Would be good to get some clarity in the WordPress PHP Coding standards as to which is preferred so we can follow that. Until then though,  BackUpWordPress consistently uses parenthesis so we should stick to that for consistency.