change return type to list in load_raw_data.

I made the mistake of not realising the dictionary was 'removing'
duplicate entries by simply not adding the 'second' reading for a
given time interval. An example of this is as follows,

there are two readings within the fifty-sixth second (E.G. 07:03:56)
but the second was being omitted from the dictionary storing the data
after it was loaded into memory.

I changed the return type to a list of tuples to preserve the raw part
of the data (I.E. multiple readings per second). The intention here is
so I can start from the 'raw' data without needing to load the data in
numerous times during run-time. I've omitted the 'Id' column because I
have no need for it in this context. If I do need it, though, I can
add an extra item to the returned tuple (I.E. add r[0] to append) .

This bug came about because I took most of the code from the initial
'load data' function. The original function converted the raw CSV data
into a dictionary which tallied the total readings per second before
returning it. This function doesn't do that. It leaves the data in a
more raw state.

src/services/io_services.py

@@ -2,10 +2,10 @@ import csv
 import datetime
 
 def load_raw_data(path):
-    data = dict()
+    data = list()
     with open(path) as csv_file:
         csv_reader = csv.reader(csv_file, delimiter=",")
         for r in csv_reader:
             if (r[1] != "Time Stamp"):
-                data[r[1]] = r[2]
+                data.append( (r[1], r[2]) )
     return data