build getters response tree in a loop

https://github.com/bitshares/gwallet/blob/master/plugins/getters/getaccount.cpp#L55-143

As the comment on the top express there is a massive amount of code in the response just to have the benefit of translate the keys of the response object. This is currently happening in all the getters.

Discussion needed about if the translation of the keys is not needed and if so, create a loop to build the tree. Add a function with the loop in a common place for commands to use.

Start with plugins/getters/getaccount.cpp around lines 55-143 and review the comment describing the response code. Determine through the requested discussion whether response-key translation is still needed, then assess the other getters before proposing a common function that builds the response tree in a loop. Done means the approach is agreed and the shared function can be used by commands.

Written by the indexing model from the issue text.