CBLT-84: add  JavaScriptCore.framework
         in   github.com/couchbase/build/tree/master/tools/iOS/bin/JavaScriptCore.framework
         from https://dl.dropboxusercontent.com/u/14074521/JavaScriptCore.framework.zip

Change-Id: I7ef6d2e5aa79ed99518576cd1525cad6a9a6c0be