update 1btcxe functions to use correct endpoints

[d3brouille]

1btcxe is the only exchange enabled.

ERROR: test_get_open_orders (clients.TestAPI)

Traceback (most recent call last):
File "clients.py", line 121, in test_get_open_orders
orders = mod.exchange.get_open_orders()
File "/path/to/local/lib/python2.7/site-packages/bitcoin_exchanges-0.0.3-py2.7.eg/bitcoin_exchanges/1btcxe.py", line 201, in get_open_orders
rawos = self._handle_response(self.send_request(params))
File "/path/to/local/lib/python2.7/site-packages/bitcoin_exchanges-0.0.3-py2.7.eg/bitcoin_exchanges/1btcxe.py", line 40, in send_request
urlpath = url + path
TypeError: cannot concatenate 'str' and 'dict' objects

ERROR: test_z_cancel_orders (clients.TestAPI)

Traceback (most recent call last):
File "clients.py", line 81, in test_z_cancel_orders
resp = mod.exchange.cancel_orders()
File "/path/to/local/lib/python2.7/site-packages/bitcoin_exchanges-0.0.3-py2.7.egg/bitcoin_exchanges/1btcxe.py", line 107, in cancel_orders
olist = self.order_list()
File "/path/to/local/lib/python2.7/site-packages/bitcoin_exchanges-0.0.3-py2.7.egg/bitcoin_exchanges/1btcxe.py", line 239, in order_list
return self._handle_response(self.send_request(params))
File "/path/to/local/lib/python2.7/site-packages/bitcoin_exchanges-0.0.3-py2.7.egg/bitcoin_exchanges/1btcxe.py", line 40, in send_request
urlpath = url + path
TypeError: cannot concatenate 'str' and 'dict' objects

[d3brouille]

the following functions are effected by this TypeError and need to be updated

• cancel_order
• create_order
• get_info
• get_open_orders
• get_trades
• get_transactions
• order_list
• trade_history

[d3brouille]

an initial drat of changes have been committed.