Fixed problem in case no suffixes exist in the list
Added `getZipContext()` that will return a copy of the context with a .zip suffix (#104)
Retrieving suffixes from filenames and nodes will now return compund suffixes with `.zip` and/or `.sha1` (#104)
Put `.sha1` and `.zip` in their own list because they at least in some cases shouldn't be seen as proper suffixes but only in combination with other suffixes (#104)
Factored out code to sign and store an artifact and moved it to `ShaSigner` (#104)
Added `canHandleFodlers()` to `ContentStore` and its implementations so we can detect if it support handling of folders or if they have to be zipped/unzipped by the CMR first (#104)
Added support for zip-before-put and unzip-after-get for those `ContentStore`s that don't handle folders as content (#104)