Add missing "ed." suffix for editor.

#4366 

The changed code takes care of the addition of "ed." and "eds." in the case of single and multiple editors. The other issue about the missing "edited by" will be addressed later on.

Output, one editor:
![selection_044](https://f.cloud.github.com/assets/4497748/1521408/4ec3ba34-4b92-11e3-8396-145e295219f2.png)

Output, two editors:
![selection_045](https://f.cloud.github.com/assets/4497748/1521413/5a827c3e-4b92-11e3-9d15-5857c2e05384.png)