Spalloc Feature Request: Allow viewing of IOBUF

[rowleya]

Splitting this from #1164 because it is a bit more complicated.
Tasks to be done:

• Fix IOBUF convertor to read from SQLite Database #1218
• Add call to let users upload the log database and incorporate it into somewhere in the spalloc database
• Upload log database to spalloc when using SpiNNFrontEndCommon#1264
• When asked to read IOBUF, use the uploaded log database table, or error if not uploaded.
• When the job ends, delete the log database entries for this job.

[Christian-B]

if the uploaded log database table does not exist I would just return the raw iobuff (as master does as there are not dict files)

The same if the short lookup code does not exist in the database