Slurm-pipeline

The `--nice` argument put into the `SP_NICE_ARG` environment variable
changed to be e.g., `--nice=50` (used to be `--nice 50` which causes
`sbatch` to complain "sbatch: error: Unable to open file 50").

Removed unused `specification` argument to `SAcct` class.

Added missing `--scriptArgs` to `README.md`. Thanks
[avatar-lavventura](https://github.com/avatar-lavventura)!

Added `env PYTHONPATH=../..` to all example Makefiles.

* Added `--scriptArgs` to `slurm-pipeline.py` to formalize giving arguments
on the command line that should be passed to initial step scripts (i.e.,
those that have no dependencies). This prevents the possibility of
putting unrecognized arguments (like `--startStep`) on the command line
which are then passed to the script steps.

Added Travis CI build messaging to IRC.