Feature/47 hhaccount conversion

# Warning
# Info
You can now pass an optional scopesize parameter when using the Household Account Conversion utility.  This parameter sets the size of the batch used to process your records.  By default, the number is 200.  In some error scenarios, a smaller batch may allow the process to complete successfully.  You can append the parameter as shown below when navigating to the URL of the conversion utility.  Here, while on na15 we'll set the batch size to 10:
https://c.na15.visual.force.com/apex/npsp__CONV_Account_Conversion?scopesize=10
# Issues
Fixes #942