close #153: modified split task to perform "split after the given pages"
close #151: renamed PdfDirectoryOutputAdapter
ref #153: missing test resources
close #154: PDFbox upgraded to 1.8.5
Removed useles null check since the page is coming from a NullsafeSet
ref #155: added params and tests for the SplitByEveryXPages task
close #155: added cli interface for the splitbyevery command