Fixed: typo in config.yml.
Add license description to README.md
Fixed date format in atom.xml
Revert "Fixed date format in atom.xml"

This reverts commit 4fcc4052d0b852c9601144fd425261b725a2041c.
Fiexed date format in atom.xml
Add meta in head.ftl
Fixed date format in template - post/date.ftl
Add reload() method to SiteConfig
Define RelatedPostsFinder
Add simple related posts finder.
Add CosineSimilarityRelatedPostsFinder - The  Cosine Similarity algorithm for finding related posts. #1
Update SimpleRelatedPostsFinder
Update site add RelatedPostsFinder support.
Update PostImpl to support RelatedPostsFinder
Add layout support for 'null', 'none'.
Fixed page url.
Move the code about pagination from Pager to PaginationGenerator
Update Preview: can reload site config and skip sass compile now.
Update opoopress maven plugin.