Merge pull request #46 from DenisKnoepfle/master

Add methods to read/write objects from/to file
Add optional FileFilter to zip methods

Files that are not accepted by the file filter will be ignored and not
added to the archive.

Change-Id: I83f661269502a4b982f2726faee438d0a93f78d2
Signed-off-by: Denis Knoepfle <denis.knoepfle@sap.com>