In an effort of ensuring consistent code style in test files as with
the "production" source code, we should run eslint as part of the
`$ npm test` script as well.

Most of the related fixes was done by `eslint` using the `--fix` argument.

Only special configuration tweaks for tests compared to the other
source code, is to allow functions declaration without names. The
rationale for allowing that in tests, is that the important reason we
have them in the source code (proper stacktraces) aren't as important
in test files.

* prevent value from being returned by Context.prototype.lookup if lookupHit is false

* add test for renderability of Array.length via dot notation

* Remove `typeof obj === 'object'` constraint in prop lookup

Allows rendering properties of primitive types that are not objects, such as a string.

* pop lookup needs to use hasOwnProperty for non-objs

* re-add  constraint in prop lookup, but make property lookups for primitives possible through dot notation

* add test to address #589 specifically

* enhance readability of primitiveHasOwnProperty and add comments to explain why it is used in one case but not the other

- Cleaner separation of responsibilities in the code between
  scanning, parsing, compiling, and rendering functions.
- Much faster

This replaces the soft escaping ('&' -> '&') with strict escaping ('&' -> '&'). This new behavior matches that of Ruby and other Mustache implementations.

Other points:
- `dot_notation` currency is changed to use an ASCII character, since the JS interpreters did not appreciate unicode.
- Forward slash is added to escape list c/o OWASP recommendations.