added experimental implementation of twitter4j over SPDY using OkHttp
set connection pool manually for Android/Dalvik platform (to avoid bad affects of TFJ-296)
added some tests
save the transport header 'OkHttp-Selected-Transport' of the last request
Merge remote-tracking branch 'upstream/master' into spdy-support
Merge pull request #123 from takke/spdy-support

TFJ-733 SPDY support