Fixed bug where header links were merging controller params instead of those sent as in the zable options hash. Created basic #click_link test helper. Implemented test asserting clicking column header reverses sort order.
Merge branch 'master' of github.com:derekcroft/zable
#click_link raises proper error if it can't find the link. Refactored column header link test to account for header cells using data-column attr instead of id.