Merge branch 'feature.renderer-relative-paths'

This adds relative rendering to pyramid_mako. This also adds the ability
to override assets using Pyramid's powerful asset management system to
override various assets.

It is recommended to use this over using mako.directories as a setting.

Close #10
Change unreleased to next release
Fix a few typos.
Merge pull request #14 from whiteroses/patch-1

Fix a few typos.
Fix typo.
Merge pull request #15 from whiteroses/master

Fix typo in CONTRIBUTORS.txt
allow mako.reload_templates override
remove python 2.5, why was it there??
allow relative-template lookup if not found in search paths
update docs and changelog