Increase request size limit

[Athanasius]

Checking the apache logs I spotted some 413 Too Large responses being sent back in response to /upload/ requests.

It turns out that the python bottle module has a default request body size limit of 100KiB.

It should be possible to tweak a setting to increase this limit.

We probably also want to attempt adding some logging to know the nature of the requests that were (before this tweak) failing, to be sure they're not actually bad senders in some manner.

[Athanasius]

For the record, it turned out all the 'over-sized' requests were navroute messages.

Some discussion in EDCD #eddn lead to a conclusion that probable max this could ever be is around 1.2MB (200 bytes, 6,000 jumps). We'll stay with 1MiB limit and try to implement some monitoring/reporting so we're aware if there's a need to further increase it.