SCL-ready templates

Hi,
I'd like to propose this patch, that enables generating SCL [1, 2] ready specfiles. I made the changes to the main fedora template, but they are only visible when using --scl/-c switch. I'm not sure whether changes to the main template would be acceptable for you. If not, I will be create a separate SCL template.
Thanks.

[1] https://fedorahosted.org/SoftwareCollections/
[2] http://docs.fedoraproject.org/en-US/Fedora_Contributor_Documentation/1/html/Software_Collections_Guide