[ADD] added ssl_verify=True to the head of the btcde.py file, use thi…

[holg]

Added doge and xrp to the definitions, also added ssl_verify=True to the head of the btcde.py file

[peshay]

I see you have two different changes in this PR, is it possible to split them up in two different commits?

1. Add currencies

2. Add option for ssl_verify

I think the ssl_verify = True could be an option in the Connection object, for example

class Connection(object):
    """To provide connection credentials to the trading API"""
    def __init__(self, api_key, api_secret, ssl_verify=False):

I put it in here as default False, mainly to not change the behaviour of the Code.

It would be also great if you could review unit tests and README to include, test and document your change. Thanks for your contribution!