Releases for Webform A/B Testing

* Issue #2291297 by sheena_d: Added webform_ab_views submodule, which exposes several tables to Views and adds a default view for administering Webform A/B tests.
* Issue #2334981 by visuaLatte: fix PHP error upon node presave.

Finalized initial release

An alpha release, could use some additional community testing to ensure everything is covered that needs coverage on the 2.x branch.

This release includes some performance improvements:

Changes since 6.x-2.0:

• Split node load query into three to improve performance of node load
• Index webform_ab_forms.status since it's used in a sort

Changes since 6.x-2.0-alpha2:

• When a webform is deleted, remove it from any Webform A/B tests that use it

New feature: winning conditions are now defined as CTools plugins.

This update includes an update path for sites running 6.x-1.x. I have only tested this myself, and am looking for feedback on the change. If you are using 6.x-1.x, please give this new version a try on a dev site.

7.x-1.x dev release

• Fixed error in logic that reported on pre- and post-win numbers
• Fixed divide-by-zero error when calculating percentage
• Changed default value of webform_ab_ignore_hits_from_roles variable from empty string to empty array
• Fixed typo where percent_conversions had been swapped for total_conversions in the winning conditions form
• Pass query variables along when redirecting to one of the webforms in the A/B Test (intended for things like market source ID)

Development branch