oaiharvest: conversion argument name confusion

* Adds the missing upgrade script for changes done to OAI harvest
  source arguments in f9271a0 that could cause name problems during
  harvesting when upgrading an existing installation.

* Amends the web-tests to look for the proper new name.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
I do not think this is possible on `master`:
```
In [3]: from invenio.legacy.dbquery import run_sql
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-3-a0b6a15845fd> in <module>()
----> 1 from invenio.legacy.dbquery import run_sql

ImportError: No module named legacy.dbquery
```
I guess you perhaps mean to add a ```try..except``` here to try first `legacy` then fall back?