[#1] Add core date formatting function.
[#1] Add date formatting function for Liquid.

Closes #1.
[#2] Add date formatting functions for Jekyll.

Closes #2.
[#1] Ensure that tests always run in the same timezone.

There is no guarantee that Wercker will be running in the same timezone as any development environment, so this needs to be hardcoded.
Bump version number.
Update Changelog.
Merge branch 'release/0.2.0'