buildtemplateparallel.sh - issue with input files

If I have an array of inputs like: 

in_files = ['~/data/subject_1/struct.nii','~/data/subject_2/struct.nii','~/data/subject_3/struct.nii']

The current code would turn this into the command:

buildtemplateparallel.sh -d 3 -n 1 -g 0.250000 -i 3 -m 30x90x20 -j 4 -o PREFIX -c 2 -r 1 -s PR -t GR struct.nii struct.nii struct.nii

Like this, I'm not able to run the buildtemplateparallel interface with Nipype. I think it crashes because it can't find the files. My commit changes the command to the following:

buildtemplateparallel.sh -d 3 -n 1 -g 0.250000 -i 3 -m 30x90x20 -j 4 -o PREFIX -c 2 -r 1 -s PR -t GR ~/data/subject_1/struct.nii ~/data/subject_2/struct.nii ~/data/subject_3/struct.nii

Like this the full path to structural images is passed to the command and it works.
Merge pull request #527 from miykael/patch-2

buildtemplateparallel.sh - issue with input files