dashes in path name cause predownloaded tar install to fail

When there are dashes in a directory name the fsl version parser for tar based installed fails

# make test directory

mkdir my-cool-name
cd my-cool-name
mkdir -p fsl/etc
mkdir -p fsl/bin/
mkdir -p fsl/python

tar -czf fsl-6.0.4-centos7_64.tar.gz fsl
rm -r fsl

# run the installer script
python -V # make sure python 2.x (e.g. python 2.7)
python fslinstaller.py -f ~/my-cool-name/fsl-6.0.4-centos7_64.tar.gz -d ~/my-cool-name/fsl -p -M -D