[JENKINS-23891] Redesign of configuration page

- Second "Advanced" button removed.
- It was confusing, nobody expected it there.
[JENKINS-23891] Redesign of configuration page

- Inline long descriptions changed to help strings (help icon on the right).
[JENKINS-23891] Redesign of configuration page

- Word "error" replaced by "issue", it is confusing for users.
Merge pull request #19 from mixalturek/master

[JENKINS-23891] Redesign of configuration page