#1486 [javascript] Add rule for no-else-return

[kanghj]

ESLint has this rule for Javascript: http://eslint.org/docs/rules/no-else-return.
It will be good if PMD could have an equivalent rule for no-else-return.

This should be disallowed:

    if (x) {
        return y;
    } else {
        return z;
    }

This should be what the rule enforces:

function foo() {
    if (x) {
        return y;
    }

    return z;
}

[Andreas Dangel]

This new rule will be available with PMD 5.5.0.

Commit: https://github.com/pmd/pmd/commit/9f40a707e0ff61522bb93beb998888b8dbfe4ee4

<rule ref="rulesets/ecmascript/unnecessary.xml/NoElseReturn" />