Update ruby-ansi to 1.5.0.

## 1.5.0 | 2015-01-16

ANSI 1.5 introduces one change that is not backward compatiable. The
`:clear_line` code no longer clears to the end of the line. Instead it
clears the entire line. If you have used this in the past you
will need to update your code to use `:clear_eol` or `:clear_right`
instead. In addition this release finally fixes some long time issues
with Windows compatability, and a few other bugs. Yeah!

Changes:

* Alias `:right` and `:left` as `:forward` and `:back` respectively.
* Change `:clear_line` to clear whole line, not just to the end of line.
* Add `:cursor_hide` and `:cursor_show` codes.
* Fix and adjust #rgb method to work as one would expect.
* Fix Windows compatability (old code was alwasy using stty).
* Fix duplicated hash key in chart.rb.

(taca)