Fix in Dygraph.log for IE8

In IE8, the console.log functions aren't true Javascript functions. They don't support the "apply" or "call" methods.

All Javascript code stopped working when a log message was being generated, therefor this small fix.
Merge pull request #234 from wimme/patch-2

Fix in Dygraph.log for IE8
Merge branch 'master' of https://github.com/timeu/dygraphs into bugfix_upstream
Merge branch 'master' of http://github.com/danvk/dygraphs into bugfix_upstream
Merge branch 'bugfix_upstream'
changed from Integer to int