add CsarRepository wip #17

move sessionGeneration in helper-Class
Merge pull request #37 from eiselems/17

add CsarRepository class refs #17
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
add UploadCsarService refs #19
Merge pull request #41 from eiselems/19

first implementation of UploadCsarService, needs to be extended, refs #19
add CsarFile to hibernate.cfg.xml
Merge pull request #46 from eiselems/45

add CsarFile to hibernate.cfg.xml, fixes #45