MODULES-825:  apache 2.4  mod_itk needs mod_prefork

in apache 2.4 mod_prefork can be installed along with mod_itk

On ubuntu 14.04 mod_itk library name is "mpm_itk.so" instead of "mod_mpm_itk.so".
Added an if statement that creates a symlink in case of a debian distro. this preserve old manifest behaviour in library loading while fixing ubuntu bug.
Merge pull request #944 from valeriominetti/modules-825-mod_itk-fix

Modules 825 - apache2.4 - mod_itk dependency fix
Update for using Geppetto plugin in CI
Merge pull request #946 from justinstoller/maint/master/geppetto-update

Update for using Geppetto plugin in CI
Fix uninitialized variable lint
Merge pull request #947 from justinstoller/maint/master/fix-lint

Fix uninitialized variable lint
Update .travis.yml, Gemfile, Rakefile, and CONTRIBUTING.md
Add json gem

The puppet_facts gem implicitly depends on the json gem.
On Ruby 1.8.7, json is not built in. On Puppet 2.7, it is
not explicitly pulled in by the hiera gem. So we add it
here explicitly.
Merge pull request #956 from cmurphy/master

Update .travis.yml, Gemfile, Rakefile, and CONTRIBUTING.md