Improvement method auth.verify

Before a change:

• function returns only one result "true", it does not matter to pass one or four key;
• need pass object in which array in array (double array).

Example:

var username = 'epexa';
var password = 'P5...'; // master password
// object in which the key type public key (active, memo, owner, posting), and the value of the array in the array itself is the public key
var auths = {
    posting: [['STM6...']],
};
steem.auth.verify(username, password, auths);

retrun:

true

After the changes:

• if pass more than one key, function will return an object;
• in object no need pass array in array, can just string.

Example:

var username = 'epexa';
var password = 'P5...'; // master password
var auths = {
    posting: 'STM6...',
    memo: ['STM6...]',
    active: [['STM6...']],
};
steem.auth.verify(username, password, auths);

return:

{ posting: true, memo: true, active: true }

But the edits are compatible, can still pass in object array in array!

Pull request