initial travis ci setup

Here's an initial travis ci setup -- it will do the basic build and run the nosetests. It pulls the testdata off the google code site. 

I used continuum io miniconda to install the pre-requisites since installing matplotlib and scipy with pip was painful. seems to work ok. 

to do:

* different python versions
* different numpy versions? given the issues we've had in the past this would not be a bad idea -- right now things seem stable with numpy>=1.5 but that might not be the case forever?