add signatures for wordpress up to version 3.8

Hi there! 

How's it going?

Added fingerprints for wordpress, below are the results of some tests:

```
http://opportunity/wordpress-3.4.2.tar.gz_extracted/wordpress/ [500] WordPress[3.4.1,3.4.2]
http://opportunity/wordpress-3.5.1.tar.gz_extracted/wordpress/ [500] WordPress[3.5.1,3.5.2]
http://opportunity/wordpress-3.5.2.tar.gz_extracted/wordpress/ [500] WordPress[3.5.1,3.5.2]
http://opportunity/wordpress-3.5.tar.gz_extracted/wordpress/ [200] WordPress[3.5]          
http://opportunity/wordpress-3.6.1.tar.gz_extracted/wordpress/ [500] WordPress[3.6,3.6.1]  
http://opportunity/wordpress-3.6.tar.gz_extracted/wordpress/ [500] WordPress[3.6,3.6.1]    
http://opportunity/wordpress-3.7.1.tar.gz_extracted/wordpress/ [500] WordPress[3.7,3.7.1]  
http://opportunity/wordpress-3.7.tar.gz_extracted/wordpress/ [500] WordPress[3.7,3.7.1]    
http://opportunity/wordpress-3.8.1.tar.gz_extracted/wordpress/ [500] WordPress[3.8.1]      
http://opportunity/wordpress-3.8.tar.gz_extracted/wordpress/ [500] WordPress[3.8]          
```