adding dot when parsing string templates

[botverse]

This is useful to be able to pass flattened objects to the template.

So you can do:

var user = { user: { name: 'Mark' }};
var flatUser = flatten(user); // => { "user.name": "Mark" }
var string = format('Hello {user.name}', flatUser);

[coveralls]

Coverage remained the same at 100.0% when pulling ee25752 on botverse:master into f63e51a on Matt-Esch:master.

[lslalbai]

Probably should also add "." to string-template/compile.js