Add EL7 support to x86_64 build

Based on @smith's feedback. In order for el7 to be on the frontend, a change needs to be made in this file. 

According to Redhat, there will be no 32 bit build so only making the change to the x86_64 portion of the json file.
Merge pull request #232 from yvovandoorn/patch-1

Add EL7 support to x86_64 build