General tidying and usability imrpovements

- I added padding/margin in places to make it more readable
- Changed the colours on the graphs
- Includes changes from this pull request also https://github.com/rlerdorf/opcache-status/pull/8

Screenshots:

![image](https://f.cloud.github.com/assets/640960/1636613/a552d7ce-57d4-11e3-9c1d-021a2f601904.png)
![image](https://f.cloud.github.com/assets/640960/1636614/aa8f8502-57d4-11e3-8807-3e0eb156845e.png)
![image](https://f.cloud.github.com/assets/640960/1636615/af902c64-57d4-11e3-8818-56835815f9a8.png)