Add example lo-res SDO imagery

Add example solar data from the AIA instrument on NASA's Solar Dynamics
Observatory (SDO) mission at low resolution (512x512).

General mission information:
* https://en.wikipedia.org/wiki/Solar_Dynamics_Observatory
* https://sdo.gsfc.nasa.gov/

Wavelength / spectral band information, and linking this back spatially
to the coronal region (height) and temperature:
* https://sdo.gsfc.nasa.gov/data/channels.php
* https://en.m.wikipedia.org/wiki/Solar_transition_region
* https://history.nasa.gov/SP-402/p2.htm

Specifics on images added:
* `wavelength_sequence`: a very short (~15 s) sequence of images across
   various wavelengths
   (does not include magnetogram data from the HMI instrument)
   * retrieved manually via https://sdo.gsfc.nasa.gov/assets/img/browse/
* `eruption_time_sequence`: a medium duration (~8 H) sequence of images
   (wavelength: 171 Angstroms: quiet corona, upper transition region).
   Show a small coronal mass ejection & some subsequent brightening
   nearby as the surrounding corona rearranges itself into a lower
   energy configuration, releasing energy in the form of minor flaring
   * retrieved via interface https://sdo.gsfc.nasa.gov/data/aiahmi/

GH-3