Minor update to readme.
Added Hodgkin-Huxley compartment example.
Implemented second part of Hodgkin-Huxley demo with Na and K channels.
Changed the constant values for the dialects into strings.
Updated nsdfwriter to store the dialect.
Added some of the file attributes described in the paper. Also added
docstrings for the same.
Updated readme fie.
Fixed ModelComponent and NSDFWriter. Added traub_et_al_2005 example.

ModelComponent - avoid accessing children before creation.

NSDFWriter - put assertion for unique dataset names in 1D case.

traub_et_al_2005 - added model tree creation and event data
saving. TODO: add uniform and nonuniform data.
Added uniform datasets to Traub et al 2005 example.
Added uniform datasets to Traub et al 2005 example. Added some of the
meta information.
Merge branch 'subhasis' of https://github.com/subhacom/nsdf into origin-subhasis

Conflicts:
	examples/traub2005.py
Merge pull request #13 from subhacom/subhasis

An example using Traub et al 2005 model added.