Map annotations custom parameters fix

Realized my custom parameters weren't working when I tried to compile for iOS 7 so i wrote a failing test and fixed it. Then i ran the test with out the fix with `rake spec target=6.0` and it failed there too. So i'm thinking this should be merged into `master` and not `edge` since it appears to be a legitimate bug.

`228 specifications (393 requirements), 0 failures, 0 errors`

[See the tests to see what this fixed.](https://github.com/clearsightstudio/ProMotion/blob/map-annotations-fix/spec/unit/map_spec.rb#L33-53)