[JENKINS-14900] [JENKINS-18662] [JENKINS-23444] Fixes for filter.

This includes fixes for following issues:
* [JENKINS-14900] (https://issues.jenkins-ci.org/browse/JENKINS-14900): Copying from workspace drops files matching Ant's default excludes since Jenkins 1.456 (see also #12)
* [JENKINS-18662] (https://issues.jenkins-ci.org/browse/JENKINS-18662): Adding exclude filter
* [JENKINS-23444] (https://issues.jenkins-ci.org/browse/JENKINS-23444): Build doesn't fail even a file in "Artifacts to copy" doesn't exist. This is a designed behavior, and the problem is the inproper help texts.

Added "Artifacts not to copy" (excluded filter):
![excludefilter](https://cloud.githubusercontent.com/assets/3115961/3563884/e876a610-0a59-11e4-99c9-68b98e65496b.png)