Update cryfs package in artful

[Sebastian Messmer]

Hi,

I'm the author of cryfs, a cryptographic file system. In the Ubuntu 
repositories, there's currently cryfs 0.9.9 in bionic and cryfs 0.9.7 in 
artful. I think it would make sense to also push 0.9.9 to artful. 
Changes between the versions are minor.

Reasoning:
Cryfs 0.9.6 and 0.9.9+ produce compatible file systems, while opening a 
file system with 0.9.7 or 0.9.8 will destroy compatibility with 0.9.6 
(0.9.6 will refuse to open it afterwards). After that, compatibility 
with 0.9.6 can be re-established by opening the file system with 0.9.9, 
so it's reversible, but it still means you can't use these versions on 
the same file system. Versions 0.9.6 and 0.9.9+ can be used on the same 
file system without issues. I recommend not using 0.9.7 or 0.9.8 anymore.

Detailed technical description (feel free to skip):
The reason is that when 0.9.7 loads an older file system (say 0.9.6), it 
asks users to "migrate" the file system to 0.9.7, even though there have 
been no storage format changes between the versions. Then, the file 
system will be marked as a "0.9.7" file system. Loading it in 0.9.6 will 
fail in the future because of this marking, even though it's still the 
same storage format. Some users have an old 0.9.6 Debian version and 
asked for compatibility. For this reason, version 0.9.9 re-established 
this compatibility by marking its file systems as "0.9.6". This means 
that cryfs versions 0.9.6 and 0.9.9 can be used alongside each other and 
run on the same file system. Also any future file systems, until there 
is a breaking change in the storage format. However, once opened with 
0.9.7 or 0.9.8, the file system marking will change and 0.9.6 will 
refuse to open it until it was opened with 0.9.9, which sets the marking 
back to 0.9.6.


Regards
Sebastian Messmer