all functions must be named rule

Disallow any anonymous (unnamed) functions. Closes https://github.com/uber/lint-trap/issues/21

jscs rules were also simplified to remove the hacky rules that achieved the same effect but with cryptic error messages.

The [pending jscs documentation pull request][pending-pr] should be updated to reflect the simplified rules and the explanation of those rules that pertain to function naming should be moved to the eslint documentation.

[pending-pr]: https://github.com/uber/lint-trap/pull/13