Update history to reflect merge of #946.
expose file path relative to source dir to liquid

Fixes #633.
fix path for posts: must include "_posts"
add cucumber tests for page.path variable
Remove code duplication
Add TomDoc for Jekyll::Command.process_site
Rescue the entire method instead of just a `begin` block
Merge pull request #952 from mojombo/refactor-commands

Remove code duplication in Build command
Merge pull request #951 from maul-esel/liquid-file-path

Expose file path to Liquid
Update history to reflect merge of #951