update dependencies, fix README typo, set license, update eslint sett…

…ings

update to ES2015

Return internal cache if get() is called with no key

* Improved code coverage in tests

* Refactored timeout storage/handling
* Removed expired checks (let timeouts handle it)
* Doc updates

* Change size, memsize, hits and misses to getters (breaking change)

* Update docs
* Update tests
* Minor code cleanups

JSHint: require single quotes

Fix a dependency screwup.

Update docs on memsize.

Bump version.

Fix tests.

Remove an unnecessary anonymous function call