Removed irrelevant STASH_DIR_ROOT
Made STASH_DIR a File
Removed unused functionality of FileStash
Made FileStash return Files and not Strings
Removed unused FileStash.allocatePortableFile(String)
Further replacements of String by File
New deleteFile(s) methods
!!! Dependent methods call not adapted, yet !!!
Running tests
Removed unnecessary comment
Parametrized test
Added IFileStash interface
New FileStashFactory (create temp, persistent and semipersistent FileStashs)
Finished feature
Merge branch 'feature/CleanFileStashLifeCycle' into develop