BUG: initial_moving_transform_com needs default
BUG: initial_moving_transform_com needs default

The initial_moving_transform_com needs to be defaulted
to false in order to maintain backwards compatibility.

When this is not default = False, it results in

initial_moving_transform = <undefined>
initial_moving_transform_com = <undefined>

Error:
Registration requires a value for input 'invert_initial_moving_transform' because one of initial_moving_transform is set. For a list of required inputs, see Registration.help()

Adding try catch block to ensure that conversions occur properly, or use defalut behavior
if boolean is undefined.

File "/Shared/sinapse/sharedopt/20130601/RHEL6/DTIPrep/BRAINSTools-build/NIPYPE/nipype/interfaces/ants/registration.py", line 471, in _format_arg
int(self.inputs.invert_initial_moving_transform))
TypeError: int() argument must be a string or a number, not '_Undefined'

pearsonlab/nipype,carolFrohlich/nipype,rameshvs/nipype,FCP-INDI/nipype,dmordom/nipype,gerddie/nipype,Leoniela/nipype,iglpdc/nipype,fprados/nipype,FCP-INDI/nipype,JohnGriffiths/nipype,dmordom/nipype,Leoniela/nipype,carlohamalainen/nipype,blakedewey/nipype,mick-d/nipype,iglpdc/nipype,grlee77/nipype,dgellis90/nipype,FCP-INDI/nipype,mick-d/nipype,arokem/nipype,dgellis90/nipype,glatard/nipype,mick-d/nipype,dgellis90/nipype,blakedewey/nipype,rameshvs/nipype,JohnGriffiths/nipype,sgiavasis/nipype,grlee77/nipype,carolFrohlich/nipype,fprados/nipype,wanderine/nipype,mick-d/nipype_source,JohnGriffiths/nipype,glatard/nipype,iglpdc/nipype,sgiavasis/nipype,sgiavasis/nipype,mick-d/nipype,gerddie/nipype,fprados/nipype,rameshvs/nipype,carlohamalainen/nipype,iglpdc/nipype,wanderine/nipype,carolFrohlich/nipype,FCP-INDI/nipype,grlee77/nipype,FredLoney/nipype,dgellis90/nipype,mick-d/nipype_source,arokem/nipype,sgiavasis/nipype,blakedewey/nipype,FredLoney/nipype,pearsonlab/nipype,pearsonlab/nipype,gerddie/nipype,glatard/nipype,pearsonlab/nipype,gerddie/nipype,mick-d/nipype_source,grlee77/nipype,JohnGriffiths/nipype,dmordom/nipype,wanderine/nipype,carlohamalainen/nipype,FredLoney/nipype,wanderine/nipype,blakedewey/nipype,arokem/nipype,Leoniela/nipype,rameshvs/nipype,glatard/nipype,arokem/nipype,carolFrohlich/nipype