Spell "TOOL_DEPENDS" correctly, not as "TOOLS_DEPENDS".
Update ruby-tw to 0.4.8.

Changes from History.txt:

=== 0.4.8 2013-08-10

* show Fav/RT count

=== 0.4.7 2013-08-09

* modify DM send dialog
* declare license in gemspec

=== 0.4.6 2013-07-28

* unescape HTML in Tw::Client#show_status

=== 0.4.5 2013-07-27

* fix listname regex, could contain '-'
  * thank you for contributing @takano32

=== 0.4.4 2013-07-14

* silent if --format option

=== 0.4.3 2013-07-02

* notify switch user
Updated net/ruby-tw to 0.4.8