Adding check for empty IN() where statements in modifier

When using modifier::where() and providing it an empty array (e.g.:
WHERE id IN ()) invalid sql was being formed.  The method now throws
an argument error if this is attempted.
Schema generated by workbench version 6.0 looks different

The new version of workbench also caught an index in the site table
(site_region_id) that has the same name as a foreign key.  It has
been renamed appropriately.
Adding new service "release_based" functionality

It is now possible to define a service as not requiring participants to be explicitely released
before they are available to that service.
Adding new base_add.allow_parent_column ivar

This feature will override the default behaviour of removing a parent's
columns from a child list widget's columns.
Fixing bug in HTML
Adding new search participant utility

Allows for complex search of participant based on address, phone, participant and note details
Merge remote branch 'origin/develop' into qa