Fix Options#fetch on Ruby 2.1.0
Allow TimeoutError initialization without arguments

Fixes failing test in Rack adapter on Ruby 2.1.0
Bump Excon

Avoids the regression in 0.27.3
Avoid Ruby 2.1.0 crash due to Excon bug when connection is failed

geemus/excon#358
Increase margin for timing assertion

Failed because delta was 0.03097:
https://travis-ci.org/lostisland/faraday/jobs/16672600
Merge branch 'ruby-2.1.0'

Closes #328