Line Graphs + Design Overhaul

Using graph.js have created 2 graphs both displaying data from the past 7 days

1. Display NPK values in ppm
2. Display Temperature in Celcius and Humidity & Moisture in % on an opposing y-axis

Graphs render conditionally when data has been received
New API endpoint /past-values to populate graphs with data

Redesigned webpage for mobile scaling in mind

assigned to @ew00710

mentioned in commit 6e7815ef

merged

mentioned in merge request !4 (merged)