viewport for IE9/10, let it can init again.

  I need to use Crafty.stop(), and then use init to restart it, actually the point is to init() again. It seems strange, but I encounter a situation that the Crafty appears in one div, then it must appear in another div. When it is in IE10, I can't init for a second time just because configurable default to be false.
Merge pull request #608 from txcodelife/develop

viewport for IE9/10, let it can init again.