Feature/merge history l2 tables (#156)

* WIP rebase

* Combine both SQL DBs

* API and DB refactor

test/dbUtils.go

@@ -0,0 +1,23 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// AssertUSD asserts pointers to float64, and checks that they are equal
+// with a tolerance of 0.01%. After that, the actual value is setted to the expected value
+// in order to be able to perform further assertions using the standar assert functions.
+func AssertUSD(t *testing.T, expected, actual *float64) {
+	if actual == nil {
+		assert.Equal(t, expected, actual)
+		return
+	}
+	if *expected < *actual {
+		assert.InEpsilon(t, *actual, *expected, 0.0001)
+	} else if *expected > *actual {
+		assert.InEpsilon(t, *expected, *actual, 0.0001)
+	}
+	*expected = *actual
+}