fix streaming example
don't run rdiscount tests on 1.9.2
lock to rdoc 1.x for now
fix rdoc version
run against 2.0.0 on travis
Fix CALLERS_TO_IGNORE to ignore Rubygems 2.0.0 require definition file

- Fixes #642
Merge branch '1.3.x' of github.com:sinatra/sinatra into 1.3.x