New dataStore implementation

* Based on pure-Go BoltDB
* Initial motivation: failure to build sqlite3 for android with
  recent Go mobile versions (mattn/go-sqlite3#201)
* Set to be used on all but Windows (where sqlite3 is in production)
  for maximum test exposure

Author: rod-hynes

psiphon/dataStore.go

@@ -1,3 +1,5 @@
+// +build windows
+
 /*
  * Copyright (c) 2015, Psiphon Inc.
  * All rights reserved.