Add timers module.

In addon-sdk there are no global timer functions, so packages that
work there need to use `timers` module explicitly. Unfortunately they
break on borwserify since timers module does not exists here.
Fix -browserify modules, broken by a97a3cc661c1806d7cd0a02890893337237d5278.

Closes #245.
1.16.7
Shim `Object.keys` so assert works in oldIE.
use Object.keys where available
1.16.8
Fix timers for chrome and write tests.
Merge branch 'patch-1' of git://github.com/Gozala/node-browserify into Gozala-patch-1
1.17.0
Fix timers for phantomjs
1.17.1
path.relative
Merge tag '1.17.2' into master-f4