Coerce from right-to-left

By default, coerce runs from left-to-right returning the version, I would discuss if it should be possible to have an option to check from right-to-left.

Actual example: 
```js
semver.coerce('test/v1.0.0/app-v1.2.3-install.exe')
//=> version: "1.0.0"
```

Possibility
```js
semver.coerce('test/v1.0.0/app-v1.2.3-install.exe', 'right-to-left')
//=> version: "1.2.3"
```