Update to use 1.3 release

[merlinstardust]

Meteor 1.3 has been announce so we no longer need to specify the release

http://info.meteor.com/blog/announcing-meteor-1.3

[sungwoncho]

If we don't specify the release, does meteor create use the latest release available, or whatever version is installed on the machine? If latter is the case, what happens if user has pre-1.3 installed?

[merlinstardust]

When I suggested that change, I thought that meteor create updated Meteor to the latest release if you started a new project. I just tested this and unfortunately am wrong.

That said, I think this is still worth doing. We have a few cases for Mantra users

1. Devs new to Meteor and Mantra. They'll be downloading the newest Meteor anyway, so it doesn't matter
2. Devs who are very into Meteor and they're looking into Mantra. The chance is high that if you're into Meteor you're keeping up with the latest releases.
3. Devs who are only playing around with Meteor. I'm not sure this group is even going to look into Mantra.

So, in any case, it seems that we should no longer have to specify a release. Moreover this can be easily handled by having the README tell devs to update to Meteor 1.3.

Making this change will make it easier going forward. Without it, every time MDG updates, the CLI has to be updated.