Accrual accounting entries are not created correctly for fixed membership

PR :https://github.com/civicrm/civicrm-core/pull/8924

Related to IIDA-64

We are going to separate the PR so that what remains does the following:

The PR calculates and stores in DB the deferred revenue transactions details for each line item for all 3 types of contribution objects : memberships, registration, contributions.
It extends the FinancialTrxnText to ensure that deferred revenue db entries are properly created.

The PR corrects the calculation of membership revenue to recognize so that it now supports fixed membership periods properly.

We will remove and then resubmit as a separate commit in this PR the code cleanup at lines CRM/Core/BAO/FinancialTrxn.php 660 - 675.

We will create a separate JIRA issue and PR for 
CRM/Core/BAO/FinancialTrxn.php 722, 725: Correct a mixup of the to and from accounts when storing deferred.

remove 961 and 1030 from PR

don't bother with l 480