Merge pull request #785 from vjuranek/JENKINS-18024

[FIXED JENKINS-18024] Avoid NPE when checking if reason why in the queue has been changed
[JENKINS-18024] Noting.
Attempting to be more robust against problems initializing this class.
https://jenkins.ci.cloudbees.com/job/core/job/jenkins_main_trunk/896/testReport/junit/hudson.tools/ToolLocationNodePropertyTest/testFormRoundTrip/
java.lang.NoClassDefFoundError: Could not initialize class hudson.model.ComputerSet
	at jenkins.model.Jenkins.getComputer(Jenkins.java:1107)
[FIXED JENKINS-16301] Optimized Fingerprint.save.
[JENKINS-16301] Need to create parent directory of fingerprint file too.
simplify isReadyToRestart
[JENKINS-15652] More clearly distinguishing the three asserts.
[JENKINS-15652] Reproduced at least one assertion failure in a unit test.
[FIXED JENKINS-15652] “Solving” errors by just return null from ALLRM.search and reducing to one-line warnings.
@kohsuke confirms that the intent of throwing AIOOBE was to track down definite code errors;
but in at least some known occurrences of this bug, the problem is invalid data:
build records on disk with <number>s that are duplicated and/or out of order.
Since that violates the precondition of the class, we do not pretend to successfully search for such records.
At some point it would make sense to have the code detect anomalous conditions and initiate a builds folder cleanup.
Take only the last build of a given number, and discard any earlier with higher number.
I.e. just set <number> to 0 or something and ignore such builds, or rename build.xml to build-broken.xml.
JUnit 4.
[JENKINS-17713] Preparing unit and functional test coverage.
Bump mailer version to 1.5
Add/fix some of polish translations
Merge pull request #796 from olivergondza/bump-mailer

Bump mailer version to 1.5
Merge pull request #797 from ljader/master

Fix polish translations
[FIXED JENKINS-17684] Integrate new Winstone with caching fix.
Do not fail startup in case ListView.includeRegex was syntactically malformed.
JUnit 4.
[FIXED JENKINS-16023] Use permalinks for as many Job.getLast*Build methods as possible.
Fixed confirmPOST JS utility not working with CSRF protection enabled.