Looks like phantomjs handles them when passed as in settings.headers (1.6-dev): https://github.com/ariya/phantomjs/blob/master/src/webpage.cpp#L362
First impl. attempt in 15059a3
refs #137 - no need for an erronously typed default for headers
As a side note and because someone asked, custom headers support requires a PhantomJS 1.6-dev build.
refs #137 - added a warning when trying to send custom request header…
…s using phantom < 1.6