fix docker run on an unknown image
Merge pull request #2869 from dotcloud/fix-docker-pull-run

fix docker run on an unknown image
fix -link parsing
Merge pull request #2870 from dotcloud/fix-links-parsing

fix -link parsing
Fix the 'but is not' typo.
fix typo in CONTRIBUTING.md
Merge pull request #2872 from goldmann/runtime_typo

Fix the 'but is not' typo
Merge pull request #2884 from nikai3d/patch-1

fix typo in CONTRIBUTING.md