Created slurm launcher for workflow plugins

This hasn't been well tested but it should work without too many issues. Of particular note are the environment variables that we're referencing. Those commands have the capability to fail with no error and need to be watched closely.
Added new interface for mesh/contour handling

Added base code, just for computing node-to-node distanced.
Some other computations could be added here.
Fix: input_spec and output_spec were not set

Fixed bug in surface-to-surface distance computation.
Implementation of surface weighting

Also fixed total weight normalization
Fixed bug

Input parameter name was used wrongly
Merge remote-tracking branch 'origin/enh/MeshAlgorithm' into enh/MeshAlgorithm
Working version

Checked that works with vtk files. Also checked for consistency when
using the same surface twice.
Fixed misnamed variable causing crash.

_sbatch_args was incorrectly called _slurm_args in one of the if
statements in slurm.py causing a crash. Added in a load .slurm to
__init__ as development env had plugins in PYTHONPATH. Moved slurm
plugin base to base.py instead of slurm.py
Added support for sbatch args to slurm module.
Added mandatory args for SLURM, fixed regex for batch job number

Added in several defaults for mandatory arguments to sbatch. Also the
regex that finds the job number was malformed and was returning 'None'
for all batch jobs. That's been fixed and is now returning jobs
correctly.
Merge branch 'master' of https://github.com/ChadCumba/nipype
Fixed a typecasting bug on some systems

strict python interp was killing o.find(<int>). typecasted to str.
Organizational changes per Satrajit's requests.

Removed base.py slurm base class and instead rolled it all into
slurm.py SLURMPlugin class, which now inherits
SGELikeBatchManagerBase. Also changed the default queue time to 1 hour
as users did not like default 48 hour queuing.
Base commit splitting the dti utilities

A new preprocess file will contain all workflows regarding preprocessing
of EPI images.
Renamed susceptibility pipeline

Since I'm to replace this workflow, I rename it with its ``classic''
name. The new pipeline will be based on the latest versions of
```fsl_prepare``` and ```epi_reg``` of FSL.

Additionally, my intention is to provide with an interface for
the new tool ```topup``` and a new workflow for T2-to-B0 registration-based
correction.
Extracted EPI-specific interfaces from utils & dti

Created a new file for adding EPI-related interfaces.
Base files for new epi interfaces

Added base classes for interfaces fsl_prepare_fieldmap, topup and applytopup
Prepare interface implemented

Start testing
Finished fsl_prepare_fieldmap interface
Added interface for topup