Updated all examples to new syntax

They all run without exceptions on 2.6, 2.7 and 3.3.

Also now using matplotlib master branch.
Because of how tox invokes pip, using the version in PyPI
won't work, as it tries to pip install numpy and matplotlib
in the some invocation. Recent versions of matplotlib have
fixed this issue, so for the time being, we'll recommend
the latest matplotlib in requirements-test.txt so that
tox works.
Test running improvements (flake8, coverage)

- tox only runs pep8 once, in the pep8 environment
  - Now uses flake8 instead of pep8, which is more comprehensive
- travis-ci should collect coverage information in Python 2.7
  - Also sends it to coveralls.io for visualization
- travis-ci (and locally running tox) now accepts / recommends
  parallelism (if pytest-xdist is installed) with
  `tox -- -n <num_cores>`
- travis-ci using wheels because building is too slow
Added check for cyclomatic complexity

- Simplified some overly complex functions,
  told flake8 to ignore others
Added delay_node example

Also made a small change in nef_summary.ipynb,
which was causing test errors in Python 3.3.
I have no idea why numpy.negative was trying
to import `winreg` on deepcopy, but there you go.