delete old files that have been replaced by a directory

Fixes #417.
Replaces #1086, more logical code.
test this fix with a cucumber feature
Add feature to test new functionality.
Remove superfluous "After" block from step defintions.
Fixed bugs with pagination in a subdirectory.
WIP – fixing tests.
Fix tests for Pager.
Add warning when pagination is enabled but no template page has been found
Fix Pager.in_hierarchy to actually do the right thing
Fix tests to match new behaviour of Pager.paginate_path
add a cucumber feature for passing parameters to includes
add support for parameters to {% include %} tags
document include tag parameters
add unit tests for include tag parameters
fix cucumber feature to obey new date format
fix liquid syntax in the docs
Add freenode verification file to jekyllrb.com.
Run site/img through ImageOptim
Added Jade Converter to docs/plugins
Merge pull request #1210 from snappylabs/jpap-docs-plugin-jade

Added Jade Converter to docs/plugins