Add Sinoe County header

Based on the [August 20th SitRep](http://mohsw.gov.lr/documents/Liberia%20Ebola%20SitRep%2097%20Aug%2020,%202014.pdf), I believe Sinoe County is the missing header in this set.

![mohsw_gov_lr_documents_liberia_ebola_sitrep_97_aug_20__2014_pdf](https://cloud.githubusercontent.com/assets/4944634/4739764/1905d362-5a07-11e4-9123-b75d366656df.png)