In order to track issues with software deployed in VM, provide more
introspective information about the VM itself.

This is needed for example for wendelin.core arrays + connections
See nexedi/slapos.core@b5a1e352

/reviewed-on nexedi/slapos!297

- overwrite slapos.cookbook:request.serialised with slapos.cookbook:request
- corresponfing md5sum updated

/reviewed-on !298

/reviewed-on nexedi/slapos!291

configure: WARNING: unrecognized options: --with-wepb

It is not needed to follow KVM development blindly and be hit by
bugs during the development.

If provided, shows instance name value in the title, so it is easier to track
and relate shellinabox with a webrunner.

/reviewed-on nexedi/slapos!295

@kazuhiko @arnau This reverts commit bf7c13c6.

/reviewed-on nexedi/slapos!296

This should fix the error below to run zope.

Error: invalid literal for int() with base 10: '10m' (line 39, in file:///srv/slapgrid/slappart7/srv/testnode/awf/inst/test0-7/etc/zope-0.conf)

Make it possible to specify the desired threshold before a requests gets saved to a temporary file instead of being read completely into memory.

@nexedi, tests do pass (I squashed commits) so unless objections today I merge it tomorrow.

https://nexedi.erp5.net/test_result_module/20180216-696E64EA

/reviewed-on nexedi/slapos!290