YAML is a nice format, very easy to read, unfortunately the Python YAML
library is very inefficient both CPU and memory wise. Loading the same
content using JSON takes 10 times less memory and time.

Since dashboard is always struggling with OOM, let's use JSON for the data
it produces.

As reference, below results of importing a 10 MB file with YAML and JSON
are presented

yaml-json $ ./test.py yaml
Time 15.507138013839722 seg
Memory (70914086, 394044198) bytes (current, peak)

yaml-json $ ./test.py json
Time 0.6210496425628662 seg
Memory (58913059, 67501787) bytes (current, peak)

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>