tested excoincial integration

[PapevisO]

Signed-off-by: Oleksandr Papevis CTO of Excoincial Exchange alexander@africunia.org

• What is the purpose of this Pull Request?
  Integration of Excoincial Exchange http API
• What is the related issue for this Pull Request (if this PR fixes issue, prepend with "Fixes" or "Closes")?
  Created issue Excoincial Exchange listing #1793,
  Purpose is an integration of Excoincial Exchange http API
• I have added Specs
• (implementing Market Ticker) I have verified that the volume refers to BASE
• (implementing Market Ticker) I have verified that the base and target is assigned correctly
• I have implemented the trade_page_url method that links to the exchange page with the base and target passed in.
• I have verified at least ONE ticker volume matches volume shown on the trading page (use script below)

client = Cryptoexchange::Client.new
pairs = client.pairs 'excoincial'
tickers = pairs.map do |p| client.ticker p end
sorted_tickers = tickers.sort_by do |t| t.volume end.reverse

[PapevisO]

Coins info page is added.
https://excoincial.com/coins-info#(coin_symbol downcase)
Special attention neccessary not to confuse CBC, GMC and NTC with other coins having same symbol.