Remove interfaceToOVSDBNotationInterface

[dave-tucker]

Depends on #116

We should look at using OvsToNative instead. This wasn't done in the original PR as I couldn't figure out how to get the ColumnSchema to be available when marshalling to a struct from JSON.

The alternative to point_up was to indirect access to the value using Value(schema *ColumnSchema) which would convert it, but I disregarded that but because you could use the wrong ColumnSchema AND you had to use NewCondition/Mutation directly and couldn't quickly create instances of the struct.
The other big issue with OvsToNative apart from needing the ColumnSchema was that it assumes sensible types, and doesn't support the "interesting" types we get from the back from the JSON Parser. E.g []interface{}{"set", []interface{}{[]interface{}{"named-uuid", "foo"}, []interface{}{"named-uuid", "bar"}}}