added Product.count & Order.count methods
fix bug where Bigcommerce would reject PUT because the body contained read-only properties.
add filter support to countable
resource.mark_dirty! - allows loading a resource from a local hash and updating it on Bigcommerce
conflict resolution; switched to new http_request vocab
pulled in count module
Version bump to 0.6.2
Regenerate gemspec for version 0.6.2