Log Message:
ruby-tw: update to 1.2.1.

Upstream changes (from History.txt):

=== 1.2.1 2017-12-10

* Fix deprecated warnings (#77)
* update gems, use twitter v6.2.0, remove yajl-ruby from dependencies (#76)

=== 1.2.0 2017-08-20

* fix --stream option (#73)

=== 1.1.0 2017-07-02

* update rubygems - parallel, rainbow, launchy #72
* fix gemspec for ruby 2.4.x #71