Adding a new ManyToMany relationship causes exception

[mopubjesse]

It seems that adding a new ManyToMany relationship, and then comparing an object seems to cause it to break.

reversion_compare/admin.py:50 sets "Field Didn't exist!" in this case, as the old reversion of the model doesn't have the value, and then reversion_compare/admin.py:124 blows up on that value.

I would propose putting a try/except and return the new list of ids in this case. I'm happy to do a pull-request if you agree this is appropriate.

Thanks.

[jedie]

Pull requests are always welcome ;)

[jedie]

@mopubjesse Does this happen in current release? Think #41 has fixed this.

[mopubjesse]

Awesome. From glancing at the code I'm not sure, I'll have to wire it up and test. I'll try to find time, just about to head out on vacation for 2 weeks. Give me a few weeks once I've gotten back to check.