Improve test coverage

[IanHopkinson]

Currently test coverage is not great:

In practice new commands are tested on the CLI. Most commands are "read" actions so relatively low risk. Potentially the commands in DEMO.md could be run in a shell script to provide some confidence that all is working.

[IanHopkinson]

Added a shell script with all the ready only commands in #21

[IanHopkinson]

Coverage now at 65% overall

[IanHopkinson]

Improving in #24

[IanHopkinson]

Test coverage is rather improved, the missing pieces are tests for the add_quickchart and add_showcase because this is potentially destructive and requires a degree of setup. Perhaps best to merge this rather than waiting for perfection

[IanHopkinson]

Added tests for add_quickcharts and add_showcase against a test dataset. Happy with this coverage, the cli is a thin skin on the hdx_utilities:

[IanHopkinson]

Fixed with #24