(doc) Sync latest CONTRIBUTING.md

This is the latest CONTRIBUTING.md from
https://github.com/puppetlabs/puppet/blob/master/CONTRIBUTING.md

The old version has out of date links.
(doc) Update links for modules

For modules, the JIRA project is MODULES not PUP.
Link to the module contributing guide, instead of core puppet
(doc) Update link to JIRA

Issue tracking has been moved from github to JIRA.
Update README.markdown
Add RHEL7 and Ubuntu 14.04.
Merge pull request #358 from sylvainkalache/master

Update README.markdown
Merge pull request #343 from skurylo/update_docs

Update CONTRIBUTING and README
Claim PE3.3 support.
Revert "Merge pull request #342 from mcanevet/feature/autorequire"

This reverts commit e5cbfbed5b411484ad04a5413090ad1d475be9fb, reversing
changes made to eb2e51f338516f3b47087543bb7a1ae1394ac4fb.

Conflicts:
	README.markdown
Merge pull request #359 from hunner/revert_autorequire

Revert "Merge pull request #342 from mcanevet/feature/autorequire"
Merge branch 'master' into 1.2.x