configs: first cut at epel-7 configs for x86_64 and ppc64
    
    - Add 'extra_chroot_dirs' config option
    - use repoquery --installroot to avoid yum cache corruption [BZ# 1029352 and 985681]
    - mockchain: avoid special characters in repoid [BZ# 1034805]
    - from Jon Disnard <jdisnard@gmail.com>:
      - implement autoreconf call in build phase of mock rpm [BZ# 926154]
      - fix --copyout by temporary drop and restore of privs [BZ# 1002142]
    - from Dennis Gilmore <dennis@ausil.us>:
      - rawhide and f19/f18 is hardware floating point only for arm, drop the unneeded configs
    - from Yann Droneaud <yann@droneaud.fr>:
      - pass root environment to repoquery calls for proxy config [BZ# 974499]
    - from Miroslav Suchý <msuchy@redhat.com>:
      - add releasever config option to configs [BZ# 1056039]