Added images for second intro to Radio Astronomy section

Images for 2_Interferometry.ipynb and 2_Interferometry_Solution
in 1_Introduction_to_Radio_Astronomy
Edit to griddata options for be matplotlib 1.4.0 compatible

Added the interp option to griddata in notebook:
1_Single-Dish_Data_Analysis.ipynb
In order to be matplotlib 1.4.0 compatible.
Added hdf5 data file for Interferometry notebooks

Added hdf5 data file for notebooks 2_Interferometry.ipynb
and 2_Interferometry_Solution.ipynb
Edits to Interferometry tutorials to unzip data file

Edits to notebooks 2_Interferometry.ipynb and
2_Interferometry_Solution.ipynb to unzip data file
kat4_int_example_github.hdf5.bz2
Merge branch 'master' of https://github.com/ska-sa/tutorials