New NTP Client (#277)

* WIP

* Added check for time out of sync

* merged upstream/master

* added tests

* Increased configuration options for NTPclient and test coverage

* removed unneeded config save at end of ntp update

* Added test for empty response to confirm it will loop

* formatting correction

* converted to pointer to allow for default allowance settings to be checked

* added readme for NTP server

* corrected some formatting

* updated configtest negativedifference value

* gofmt config_test.go for correct import order

* corrected typo value in test

* bugfix for windows newline and changes based on PR feedback

* added minus sign to output

* fixed negative number input

* Fixed spelling mistakes and removed redundant test

* reverted back to a positive number in the config instead of negative for allowednegativedifference

* restructured code for cleaner output

testdata/configtest.json

@@ -12,6 +12,15 @@
  "profiler": {
   "enabled": false
  },
+ "ntpclient": {
+  "enabled": 0,
+  "pool": [
+   "0.pool.ntp.org:123",
+   "pool.ntp.org:123"
+  ],
+  "allowedDifference": 50000000,
+  "allowedNegativeDifference": 50000000
+ },
  "currencyConfig": {
   "forexProviders": [
    {