Fix MatchError during default value parsing, ignoring more time default ...

...functions

See https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/scalaquery/CvaWXZ52Ong/HpPcpt07k50J

no review

/cc @szeiger 
good point. It's SQL standard, but you are right. The lifted embedding does not support CURRENT_TIMESTAMP as a default.