update dev-dependencies (#53)

Signed-off-by: Marco Casula <[email protected]>

Fix HandValue Hi must be equal to Lo when Hi > 21 (#52)

* impl test case for #51
* return hi == lo when hi is over 21
* ref test cases to match the fix for #51
* upgrade version
* standard format

close #51 

Signed-off-by: Marco Casula <[email protected]>

Impl getHigherValidValue (#50)

* impl test case for #49
* impl getHigherValidValue to ensure the higher valid number in `handValue`
* impl getHigherValidValue in `getPrize` fixes #49

Signed-off-by: Marco Casula <[email protected]>

increment version to 0.6.0 (flowtized)

Signed-off-by: Marco Casula <[email protected]>

More ES6 (#29)

* Replace `Object.assing` with spread/rest operators
* Fix main lib export: Export without `default`

update package

Signed-off-by: Marco Casula <[email protected]>