Improved widget management tools

[clpetersonucf]

As Materia continues to become further embedded at UCF and other institutions, one notable pain point is the lack of tools around widget management. These features could be built into the existing widget admin panel.

This feature is likely to be a post-11.0 release, once the django rewrite is wrapped up.

Additions to widget table:

• Widget install source (e.g., GitHub URL). Would likely have to be whitelisted or conform to a specific URL.
• Widget installed version.

Additions to admin panel:

• Easy download and install/update from source location (GitHub).

Other Enhancements:

• Check for updated versions on a periodic interval and notify when new versions are available.
• List potential widgets to install from a source registry (the official widget gallery or some variation of it).