Empty file for windows docs.
Some beginning collection for Windows users.

Leaving the office so it's a bit unkempt.
Add additional information about encoding issues on Windows
Add note about auto-regeneration
Add block of code which should be added to Gemfile for Windows listen compatibility.

Closes https://github.com/mojombo/jekyll/pull/1720
Add syntax for mercenary CLI engine by @mojombo
Fix serve -> server alias, ensure --drafts is mapped to show_drafts
Switch from commander to mercenary in gemspec
Let jekyll-import specify subcommands and their options for each importer.

@mojombo, this look better?
Check if JekyllImport is defined using Object#const_defined?
If no args are given, then list possible importers.
Remove 1.8.7 from Travis build spec
Require Ruby version >= 1.9.2 in gemspec
Remove weird 1.8.7 workarounds in features env
Don't check for >= 1.9 in Rakefile
Remove Ruby <1.9 core extensions
Remove checks for Ruby 1.8.x
Add tests in all the time that was omitted for Ruby 1.8.x
Remove File.read_with_options patch to allow 1.9 and 1.8 to behave the same
Implement group_by Liquid filter & tests.