change from FileInputStream to InputStream

*other services will usually supply an InputStream
Merge pull request #52 from eiselems/19

change from FileInputStream to InputStream, fixes #19
Replaced PersistenceException with Exception
refs #53
moved operation to constructor, refs #22
Merge pull request #54 from TKosch/53

Replaced PersistenceException with Exception, fixes #53
Merge pull request #55 from przytads/22

moved operation to constructor, fixes #22