Store dates in Mongo as ISODate rather than Integer #1228

I found +(new Date) in the following files:

* examples/unfinished/benchmark/benchmark.js
* examples/other/quiescence/quiescence.js 
* packages/livedata/livedata_server.js 
* packages/accounts-base/accounts_server.js 
* packages/accounts-password/password_server.js 
* packages/livedata/sockjs-0.3.4.js 
* packages/minimongo/minimongo_tests.js 
* examples/other/template-demo/client/d3.v2.js 

I updated only the code that would be used to generate production data and cause difficulties in querying the data with the MongoDB Aggregation Framework.

* packages/accounts-base/accounts_server.js
* packages/accounts-password/password_server.js