Updated ruby22-squib to 0.13.1.

## v0.13.1 / 2017-01-06

Bugs:
* New Windows installations break because Rubygems looks for 1.15.4 and it's not there (yet). Locking into Cairo 1.15.3 and being more conservative from now on.

## v0.13.0 / 2017-01-04

Features:
* `save_pdf`'s `crop marks` have a `:full` option that draw lines across the entire page.

Bugs
* Fix `Squib::DataFrame#to_pretty_text` modification issue (#191)
* Downgraded Pango et al. back to 3.0.9 from 3.1.0 because there are bugs in the new gobject-introspection library.

Chores:
* Shrank the gem itself by ignoring test data. From about 5mb to 64kb - yay!
* Bump roo to newest version (2.7.0).
* Bumped Nokogiri to latest version (1.7.0).
* Re-organized the samples folder for better regression and sanity testing prior to release.

(wiz)