try to adopt rest-core 2.0. sorry don't know if this would work or not

because i don't have a plurk account nor an app to test out?
twitter_agent.rb: force loading the result with tap
Merge branch 'adopt-rest-core-2.0' of github.com:godfat/s2sync_web

Conflicts:
	Gemfile.lock
	twitter_agent.rb
Use rest-core 2.0
Disable Rack::Protection::HttpOrigin to avoid session issue under reverse proxy env