Remove catalog and data browser Flask web apps #1103
This pull request removes the catalog and data browser Flask web apps.
I do think we should allow widgets or web GUIs in Gammapy as long as they are almost exclusively Python code and thus not very hard to maintain and potentially useful to a good fraction of users. Concretely Bokeh is something to look at, and in the coming weeks JupyterLab will be released, which is the evolution of the Jupyter notebook and Jupyter widgets that we already use and that many devs and users are familiar with and like (see e.g. http://blog.jupyter.org/2016/07/14/jupyter-lab-alpha/ or the upcoming http://go.continuum.io/registration-jupyterlab-next-generation-ds-ide/ and https://conferences.oreilly.com/jupyter/jup-ny ).
So if anyone is interested to implement Jupyter widgets or other GUI functionality (or just example docs) how to browse gamma-ray data or catalog data, please open a new issue if you have any questions or a pull request if you have implemented something.
For catalog data there's also http://gamma-sky.net/#/cat by now for cases where you just want to look up some info on a given source.