Spec clean up
    
    - Drop POD patch, fixed in 1.67
    - Fix source URL to refer to current upstream maintainer
    - Escape macro used in changelog (#1527541)
    - Drop legacy Group: and BuildRoot: tags
    - Drop %defattr, redundant since rpm 4.4
    - Use %license where possible
    - Drop redundant buildroot cleaning
    - Don't need to remove empty directories from the buildroot
    - Simplify find command using -delete
    - Specify all build dependencies
    - Make %files list more explicit
    
    None of these changes break compatibility with EPEL-6, the oldest
    currently-supported target.