implemented repository for csarfile, fixes #18
propagate exception, review #18
refactor FileSystem

-use UUID to generate filenames
-retrieval/deletion by absolute paths

add new method to save temp file

remove id from method header
Merge pull request #38 from przytads/18

implemented repository for csarfile, fixes #18
Merge pull request #40 from eiselems/fileSystem_refactoring

refactor FileSystem