Python Poloniex Versions Save

Fixes websocket callback messages #205

Websocket fixes and features

added cancelAllOrders and cleaned up examples

fixed subscribing to 'account' made the default class the helper and the websocket class is 'PoloniexSocketed'

Adds websocket support and pypi deployment

Moved helper methods to its own class, PoloniexSocketed is now Poloniex

Change Log:

• #152 #154 captured exceptions by retry are logged at debug level
• #157 added dictionary websocket ticker example
• #169 #167 added proxy support
• #171 added limit param to returnTradeHistory
• typos

Change Log:

• https://github.com/s4w3d0ff/python-poloniex/commit/5af30d1801bddcf09e6040e84f99e91b493a81f6 add confirming arg for transferBalance
• https://github.com/s4w3d0ff/python-poloniex/commit/0bf4868c1d2aad59a4fbe9f4bd7544f8e96564ad created code of conduct
• https://github.com/s4w3d0ff/python-poloniex/commit/31a996443f6e0faf0e9dbe576ea86a1bc6a5d447 created contributing.md
• https://github.com/s4w3d0ff/python-poloniex/commit/2e4e517d0eeefab560f2e12b8609238b7a49d288 https://github.com/s4w3d0ff/python-poloniex/commit/d86e5c754592675beffd2bdf14ea58806ee7e738 added dumb ticker and websocket ticker
• #136 fixed chart.py example for python2
• other minor changes

Change Log:

• #131 fixed logging of invalid json, now retry captures any 'please try again' errors, other cosmetic changes