Default DiskUsage HealthMetric unhealthy limit to 500MB instead of 2GB

[bplattenburg]

Also includes a minor refactor to align the logic flow and bytes math to match how DittoSwiftTools does things (everything in bytes)

Closes #87

[bplattenburg]

@rajramsaroop I tried to refactor a bit to address your feedback and bring this closer to how the DittoSwiftTools version works

[rajramsaroop]

@rajramsaroop I tried to refactor a bit to address your feedback and bring this closer to how the DittoSwiftTools version works

In general (personally) I think the same API's but for different platforms should match (in terms of naming, input/outputs etc), but anything that might be platform specific should look like what a developer of that platform expects. I think what we have here is OK for now (since we're favoring speed over perfection lol).

[bplattenburg]

@rajramsaroop when you get a chance, can you rough out the refactor you think makes sense into its own issue for this repo? Its worth revisiting and making sure we've decoupled the UI and HealthMetricProvider portions of this tool fully.