Refactor URL processing/generation into separate module

This is done to prepare for improved permalink generation
for URLs containing special characters, as proposed in
issue #782
do not force the permalink to be a dir if it ends on .html

Fixes #798.
test per-post permalinks

Add tests for setting a permalink on a post (in YAML frontmatter),
both the "old way" (generating an index.html) and with an .html ex-
tension.
Created new changelist page. It currently looks bad.
Cleaned up the formatting of changelist page and removed HEAD section.
Rake task added to move History into site and update its formatting.
Manually fixed formatting for now.
Reverted my upgrading.md to fix merge conflict.
Merge branch 'master' into changelist_page
Moved changelist to /history directory.
Updated rakefile to support new directory and parsing structure.
Added /history directory to the gemspec.
Programatically create github issue links via rake task.
Merge branch 'master' into changelist_page
Needed to be issues and not issue in the url. Regenerated file.
delete old files that have been replaced by a directory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 note to upgrading docs on new config file options.
Switch cucumber features to use iso dates
Combined two features into one