Update CI constraints

Merge branch 'cache-inbound-oob'

* cache-inbound-oob:
  Intrument cacheOOB
  Fetch any OOB URL from route and cache in jingle store
  Set up structure to cache OOB coming from a direct message route

Fetch any OOB URL from route and cache in jingle store

Now we actually cache the data.  Always assumes URLs are HTTP, but they always
are in practise and if one is not it will simply fail and in case of any error
we just pass the oob element through unmodified.

Also build for Ubuntu LTS

Mostly because that's what psycotica0 uses.