<install> Bug 976874 - Remove abrt-addon-python if necessary

https://bugzilla.redhat.com/show_bug.cgi?id=976874

abrt-addon-python does not play nicely with the python cartridge, remove
abrt-addon-python only if the following conditions are met:
1) RHEL 6.4 (RHEL 6.5 will contain an update to abrt-addon-python)
2) abrt-addon-python installed
3) python v2 cart installed
Merge pull request #30 from detiber/killabrt

<install> Bug 976874 - Remove abrt-addon-python if necessary