MXS-1300: Fix logging and maxscale alteration

The alterations to logging and maxscale were sending malformed JSON to
MaxScale. Boolean values weren't converted to JSON booleans but were sent
as strings.

maxctrl/lib/common.js

@@ -142,6 +142,14 @@ module.exports = function() {
 
     this.updateValue = function(host, resource, key, value) {
         var body = {}
+
+        // Convert string booleans into JSON booleans
+        if (value == "true") {
+            value = true
+        } else if (value == "false") {
+            value = false
+        }
+
         _.set(body, key, value)
         return doRequest(host, resource, null, { method: 'PATCH', body: body })
     }