add test case for variable include tag in a loop
fix include tag: don't store variable value

This fixes the bug reported in #1495 (comments).
Update history to reflect merge of #1726
Use Pathname#to_s instead of Pathname#to_path

Fixes #1723.
Update history to reflect merge of #1730
Remove all the docs for migrations and link to http://import.jekyllrb.com
Update history to reflect merge of #1732
Enable Travis' bundle caching

It should speed up the builds significantly. See
http://about.travis-ci.org/docs/user/caching/#Bundler for more details.
Update history to reflect merge of #1734
Update link to example Rakefile to point to specific commit.

The link was pointing to the latest version of the file which had been changed and no longer provided the intended example.
Update history to reflect merge of #1741