v3 "Exception wrapping data"

[Cantor, Scott]

> I happened to see these in my process logs today (my relevant logs only go
> back a week, but I've got thousands across the past week):
> 
> 
> 2016-02-09 21:12:50,113 - ERROR
> [net.shibboleth.utilities.java.support.security.DataSealer:292] - Exception
> wrapping data
> 
> java.io.UTFDataFormatException: encoded string too long: 104770 bytes

The core bug here was an actual limitation in Java because it writes out length-prefixed UTF-8 with a 16-bit length field. I patched that with a chunking loop that will allow storing of reasonable data sizes. A separate issue is of course keeping that from growing, which I'll have to research but shouldn't really be done at this layer. The session cache probably just needs limits included.

-- Scott