java: Get the DatabaseOptions.rootDir to work

Note that the rootDir is not exposed in the io.v.syncbase.core. The
purpose of this CL is to get all the high-level API tests from
SyncbaseTest to work. This change also adds the ability to shutdown
syncbase. The high-level API tests are reconfigured to use and empty
list of mounts points speed up the shutdown.

MultiPart: 3/3
Change-Id: I142966b1a2128d0b3de136d41fb0504f254ba672
diff --git a/SyncbaseCore/Source/Syncbase.swift b/SyncbaseCore/Source/Syncbase.swift
index 9ffe8bd..6147c86 100644
--- a/SyncbaseCore/Source/Syncbase.swift
+++ b/SyncbaseCore/Source/Syncbase.swift
@@ -15,7 +15,7 @@
   /// Private constructor -- because this class is a singleton it should only be called once
   /// and by the static instance method.
   private init() {
-    v23_syncbase_Init(v23_syncbase_Bool(false))
+    v23_syncbase_Init(v23_syncbase_Bool(false), try! "root-dir".toCgoString())
   }
 
   /// Create a database using the relative name and user's blessings.