Strengthened deathwatch tests and uncovered a bug wherein watching a dead actor results in a termination message from the wather (as opposed to the watched actor)
Added spinoff.actor.spawn as a shortcut to get_context().spawn()
Removed util.testing.evseq
Bumped version to 0.7.18
Clearer exception messages when _BaseCell.get_child or Node.lookup_str are passed bad parameters
Corrected the default_content_type parameter to contrib.http.Request to content_type
Merge pull request #22 from cizra/fileref-deletion-errors

Added error handling for fileref deletion
Added spinoff.actor.quick.{actor, process}
Small cleanup WRT error responses in s.contrib.ft.FileRef.{upload and delete} and the corresponding s.contrib.ft.Server parts
Fixed a bug in fileref upload error handling