Options#fetch should not return the default for false or nil values.
Merge branch 'master' of https://github.com/benburkert/faraday into default-fetch-fixes
stop shadowing Faraday::Options
make Faraday::Options#fetch more like Hash#fetch
Merge pull request #320 from lostisland/default-fetch-fixes

make Faraday::Options#fetch more like Hash#fetch