Allows `.` (dot) in for-of key

This fixes an issue where the key in a for-of loop contains a dot, for example, if the data looks like this:

"Page.2" : {
pageName: "Page.2"
}
can-stache could not read/render item.pageName where item is the object above. Now the dot or dots are escaped which allows the value to be read and rendered.

#698