Add currency pairs api call and lazy init results.
Merge remote-tracking branch 'upstream/develop' into develop

Conflicts:
	xchange-bter/src/main/java/com/xeiam/xchange/bter/service/polling/BTERPollingTradeServiceRaw.java
Fix currency pair deserializer to handle symbols > 3 char.
Merge pull request #335 from jamespedwards42/develop

Lazy Init Exchange Symbols From Server Instead Of Static Config