Fix DB schema to match GTFS specification

The fact that the DB schema was incompatible with the GTFS specification
(https://developers.google.com/transit/gtfs/reference) caused the app to
stop working.

This CL fixes this issue.

Change-Id: Ic8603d8026d8cee4853b02f5d67ec7e068b982d4
diff --git a/inc/gtfsHandler.php b/inc/gtfsHandler.php
index a6d8aa1..5ea3431 100644
--- a/inc/gtfsHandler.php
+++ b/inc/gtfsHandler.php
@@ -137,11 +137,11 @@
     ],
     "shapes" => [
       "columns" => [
-        "shape_id" => "TEXT PRIMARY KEY",
+        "shape_id" => "TEXT",
         "shape_pt_lat" => "FLOAT NOT NULL",
         "shape_pt_lon" => "FLOAT NOT NULL",
         "shape_pt_sequence" => "INT NOT NULL",
-        "shape_dist_traveled" => "FLOAT NOT NULL"
+        "shape_dist_traveled" => "FLOAT"
       ]
     ],
     "frequencies" => [