Remove version from badge edit/create screens

[davelester]

The version field included in WPBadger is a user-editable field, when it probably should not be. According to the badges spec, the version refers to the spec version that the assertion is compatible with. Right now, users enter whatever version they want (as long as it in n.n or n.n.n format) in the version field. The beta spec version should be 0.5.0.

There are potential migration problems as a result of this. It would be bad practice to change assertion files that have already been generated, but since assertion files are dynamically generated how will the plugin manage multiple versions for each badge? Definitely wish I caught this earlier..

I may consult with some of the most-active WPBadger users to come up with a solution. Also, @brianloveswords do you have any suggestions about dealing with this from the perspective of the OBI?