Spec clean-up
    
    - BR:perl(ExtUtils::Manifest) and perl(Test::More)
    - Drop workarounds for no-longer-shipped signature test
    - Drop BR: perl(Module::Signature)
    - Don't need to remove empty directories from buildroot
    - Don't use macros for commands
    - Drop %defattr, redundant since rpm 4.4
    - Make %files list more explicit
    - Use tabs