Hide role dropdown on user page if user is owner

Closes #3764
Validation fix for number of posts/page

closes #3641
- Reworded error messages, remove “please” (credits go to @YouriAckx)
Revert post status on failed save.

Refs #3667, Refs #3776
- If saving a post fails, revert its status back to the
  pre-save value.
- Added tests to check post status after failed save attempt
  on both new and existing posts.
Improve documentation section in CONTRIBUTING.md
Open the e-mail sending support page in a new window.
Added target="_blank" to all links that go to the support page.
Merge pull request #3788 from jillesme/master

Open the e-mail sending support page in a new window.
Merge pull request #3769 from novaugust/iss3764

Hide role dropdown on user page if user is owner
Restore email templates in npm package

no issue

- apparently npmignore's globbing rules are different to grunts. The rule *.html has been interpretted as all html files and the email templates are missing from the npm package.
- this fix tells npm not to ignore email templates, so that they will be present in the next release
Display correct new Ghost version

closes #3790
Merge pull request #3670 from felixrieseberg/iss3641

Validation fix for number of posts/page
Merge pull request #3785 from jaswilli/post-status

Revert post status on failed save.
Merge pull request #3791 from ErisDS/issue-3790

Display correct new Ghost version