removing accidently added HelloWorldBuilder
use guava splitters for more robust string splitting
enhancing error detection

 * when creating or recreating a chroot environment
 * when copying chroot environments to the job
adding missing negation on isFileIntact
fixing null pointer exception
use build.getBuiltOn(), to get node
split all kinds of newline in in packages string
copy chroot images 'local' on the node

the images were created on the node, but when copied into the workspace on the
same node, they were accidently copied over the network
removing useless 'tarBall' field from ChrootToolsetProperty
Merge pull request #3 from rmohr/master

various fixes

* fixes a null pointer exception when building on a slave node
* uses 'local' copying of chroot image FilePaths
* removes useless tarBall field from ChrootToolsetProperty
* detects aborted/failed chroot environment initialization