add Decimal for numeric values in Documentation
rename get_exchange to new_exchange
add tests for exchanges listing
add first tests for Bitcurex and Bitfinex exchanges
ignore ssl certificate for bitfinex
introduce ticker object with Decimal('NaN') as default value
add ticker test for bitfinex
ticker test for bitstamp
ticker test for btcchina
ticker test for btce
campbx ticker now returns values as decimal
ticker test for campbx
ticker test for cryptotrade
ticker test for cryptsy
ticker test for intersango
ticker test for justcoin
ticker test for localbitcoins
ticker test for mtgox
ticker test for rock trading