Add 'nin' and 'in' to query.

This methods are used with field name and array.

db.query().nin('fieldname',['a', 'b']);
db.query().in('fieldname',['a', 'b']);

Read below for more information.
http://docs.mongodb.org/manual/reference/operator/query/in/
http://docs.mongodb.org/manual/reference/operator/query/nin/
Fix bugs in collection.find().

QueryOpts is immutable, skip() and batchSize() doesn't change itself, it
creates new one.

Both skipN and batchSieN has default value 0.
Make metrics disablable.

Beyond uses sigar for metrics, but there is a problem to use sigar
library in production mode. So disable it until fix the problem.
Implement rhino source provider for assets.
Use AssetsModuleSourceProvider.

This patch modifies to use AssetsModuleSourceProvider for libraries and
use UrlModuleSourceProvider for logic code.

Currently, AssetsModuleSourceProvider has a bug so it cannot uses with
sandboxing.

And this patch also moves javascript libraries to core/public to add
them assets.