Add 'Download' to chart options

[kilemensi]

Description

Since the chart object is created and configured in Wazimap, it is necessary to override it by implementing the chart creation and configuration in HURUmap.

Fixes CodeForAfrica/HURUmap-Apps#43, CodeForAfricaLabs/wazimap#1

Type of change

• [X] New feature (non-breaking change which adds functionality)

Screenshots

Checklist:

• [X] My code follows the style guidelines of this project
• [X] I have performed a self-review of my own code
• [X] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

[kilemensi]

When you get the time, please look at this @DavidLemayian. Philip is on a well earned leave.