supress alphanum callnumbers

Closes #566 :unamused: 

#### Before - 10412502
![screen shot 2014-08-15 at 8 17 50 am](https://cloud.githubusercontent.com/assets/1656824/3934871/0a04b858-2490-11e4-9b41-acd86bf3eb02.png)

#### After - 10412502
![screen shot 2014-08-15 at 8 18 00 am](https://cloud.githubusercontent.com/assets/1656824/3934884/14a1ac30-2490-11e4-8d27-828c3d3915ca.png)