Audit charging of per-kilobyte fees

_From @theoreticalbts on July 31, 2015 15:22_

Any operation with potentially unbounded size needs to charge a size fee. Determining whether an operation is variable-size is non-trivial. An operation is variable size if it contains a `vector`, `flat_set` or other potentially variable-size element.

Note that this containment may be through any number of intermediate `struct`s. For example, any operation which contains an `authority` has potentially unbounded size.

We should be able to audit this in a semi-automatic way with logic similar to `js_operation_serializer` which traverses all operations, and noting any variable-size types found (in any number of sub-structures), allowing us to flag each operation as variable-sized (or not). We will still have to manually specify whether any base type is variable-size or not.

_Copied from original issue: cryptonomex/graphene#216_

Start by locating and reading the existing js_operation_serializer traversal and the operation and base-type definitions it processes. The audit should follow variable-size elements through nested structs, record which operations can be unbounded, and leave each base type explicitly classified so per-kilobyte fee coverage can be reviewed.

Written by the indexing model from the issue text.