* replace pymarketcap with coinmarketcap
* fix tests to use coinmarketcap instead of pymarketcap
* use arraypos 0
* update setup.py from pymarketcap to coinmarketcap
* Add test to check for unsupported Crypto currency
Result in a speed up of the unittest from 60s to 4s
Because it cost time to load Pymarketcap() every time we create
a CryptoToFiatConverter, it worth it to change it into a
Singleton.
