Fixed NEB runs

Here are the changes I made to get the NEB code to work. 

You would probably not want to merge jasp_extensions.py as it contains changes I made to get it to work on the SGE scheduler. I tried to make it such that the PBS behavior is unchanged (if you set JASPRC['scheduler'] = 'PBS']), but it is not tested. In jasp_neb.py there is another line (https://github.com/prtkm/jasp/blob/master/jasp/jasp_neb.py#L211), that I added to get both SGE and PBS to work.