New update_fsl_package script

Dedicated script for updating FSL conda packages. Does not support installation of new packages at this point in time.

Also added the fslipython wrapper for $FSLDIR/bin/ipython

bin/fslipython

+#!/bin/sh
+
+if [ "$FSLDIR" = "" ] ; then
+  echo "FSLDIR has not been set!"
+  exit 1
+fi
+
+exec ${FSLDIR}/bin/python -m IPython "$@"