Fixes for crontab and proposals to hashed crontab

Fix for JENKINS-11353
thanks.

[JENKINS-12518] table rows with id= for keyboard shortcuts plugin

[FIXED JENKINS-12357] Crontab#ceil may stuck in an infinite loop or may return an incorrect value if day of week is 7 (=0, Sunday)

To use @test(timeout), inheritance from TestCase should be removed

They look different, but had been same. See 921359c1

Fix multi submit with shortcut key

This reverts commit 47c520b1.

I see it clearly now. I was bit concerned about double-counting,
because one expects that totalSnapshot (total # of executors)
includes idle executors. But this is not the case, and in any way
this code should be read as (x==0 && y==0 && z==0) not (x+y+z==0)
conceptually. So reverting my revert.

This reverts commit 5a95baff.
Oops, I don't know about this. More comments in
https://github.com/jenkinsci/jenkins/pull/362

Formatting error in the rootDN inference code. It shouldn't include
attribute name.

co-locating IntelliJ version with Eclipse version since they are the same thing written in two different languages

Prevent Jenkins from over provisioning when there is only one slave, which is still connecting.