Bug 3820: Add changes to MEMBERS MODIFY logaction

Bug 3820: Add changes to MEMBERS MODIFY logaction

This patch attemps to add a more refined and detailed info structure
detailing what fields were changed and what they were changed from and
to.

Test Plan: Enable BorrowersLog in the system preferences and undertake a
series of borrower detail changes.  Go to view the actionlogs and note
that MEMBER MODIFY logs now detail what fields you have changed using
the following form:

  { FIELD1: { before: BEFORE_VALUE, after: AFTER_VALUE } }

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Charles Farmer <charles.farmer@inLibro.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>