Add get_currency_me() method.

[ghost]

print(y.get_currency_me('snt'))
-> {'currency': 'snt', 'balance': '9999.98', 'locked': '0.0'}

[imlonghao]

Hi,

Thanks for your patient finding my another typo.
I will merge 84444ae into master branch later, and a new version v0.2.1 will be released for this commit.

I am sorry to say that at this time I will not accept the new method get_currency_me for the following reason:

1. The official API doesn't provide this method.
2. It's easy for programmer to achieve this method, they can do that in their code.
3. If I merge this method, I need to write another docs for this, which I don't want to do.

:)
Thank you