Handle users' copy paste better.

[hrishikeshs]

The parsing logic has a bug where it does not handle the case where a string value field of a json document is not updated properly when it contains a string that has : in it. An example of this would be:

{
 name: "mongo",
 type: "db: jsondb"
}

This will not update the document correctly.

[hrishikeshs]

The above example works fine on the latest master. But when users copy paste json from external sources, the editor messes things a little. I'm updating the bug to reflect that.