Adding a CONTRIBUTING document

Adding a CONTRIBUTING document to take advantages of this:
https://github.com/blog/1184-contributing-guidelines
add comps files for fedora19

copy fedora18 to fedora19 and remove those packages which made it to main Fedora 19
Issue 1712 - Incorrect error notification when creating user

No need to validate rolename when role  == self_role
967103 - RAM and Cores limit displayed wrong

katello displayed RAM in megabytes in some places and gigabytes in some
other places. Making it consistent throughout the application.
969229 - require minitest for installation to support rails console

due to rails issue 6907 running rails console in production
requires minitest to be installed.  Since this is a highly
valuable debugging tool, we should allow rails console to be
run without additional packages to be installed
Merge pull request #2381 from xsuchy/pull-req-comps-f19

add comps files for fedora19
Merge pull request #2392 from komidore64/ram-in-GB

967103 - RAM and Cores limit displayed wrong
Merge pull request #2405 from jlsherrill/require_minitest

969229 - require minitest for installation to support rails console
Merge pull request #2373 from mptap/rolename_validator

Issue 1712 - Incorrect error notification when creating user
Merge pull request #2333 from daviddavis/temp_1368975142

Adding a CONTRIBUTING document
We need new ldap_fluff for Fedora