Univalue's parsing of \u escape sequences did not handle NUL characters
correctly. They were, effectively, dropped. The extended test-case
fails with the old code, and is fixed with this patch.
Make sure that chainparams and logging is properly initialized. Doing
this for every test may be overkill, but this initialization is so
simple that that does not matter.
This should fix the travis issues.
Jonas Schnelli