Minor tidy up for beta release.
Added new config option 'default_interactive_plot_type' to hedgehog_gui.yaml. This can be used to generate SVG interactive plots instead of the default interactive plots which require Flash.
Merge pull request #13 from saradickinson/beta_release_cleanup

Add new interactive plot type config option and do beta release prep
Database schema changes: splitting plot table into dataset and visible_plot tables + view plot
Refactoring of tools scripts