Fixing typos on French translation (in the "Administrer Jenkins" page)

- "systême" --> "système" (5 times)
- double quotes

Conflicts:
	changelog.html

Javadoc was quite confusing as the build is actually a FAILURE if tearDown returns false and not ABORTED

Conflicts:
	changelog.html

If the user still has the API token that's generated from secret.key,
don't accept that.

Hopefully this is the last fix

If JENKINS_HOME is created by a post SECURIT-49 Jenkins (LTS, and other
variants), then there's no need to alarm the user.