Add a way to serialize attribute value
Currently there is deserializeValue but no serializeValue, you have to serialize the whole attribute. This was thought for our JSONRPC api, but the REST one gives access to each attribute directly, so we need a way to serialize the data directly.
Expected behavior
Method in Attribute to serialize its value, which does the opposite of deserializeValue. (doing $attribute->deserializeValue($attribute->serializeValue($attribute->getValue()))
should not change the attribute value)
Benefits
Will be used by REST API.