Create log pages

The creation of log pages should fix [SPARK-608](https://spark-project.atlassian.net/browse/SPARK-608).
The following changes have been made:
- Add new "/logPage" path to give visual log exploration via pages
- Move some unit tests to correct package
- Update existing "/log" path to use newer options (offset, byteLength)
![log page](https://f.cloud.github.com/assets/4754931/785669/9d868e62-ea8a-11e2-8b9e-5844a40f2b8a.png)