Renamed get/setTimestamp to get/setValidFrom.
Merged back with latest changes.
Merge branch 'master' of https://github.com/JavaMoney/javamoney.git

Conflicts:
	money-api/convert/src/main/java/javax/money/convert/CurrencyConversionException.java
	money-api/convert/src/main/java/javax/money/convert/ExchangeRateBuilder.java
	money-ri/src/main/java/net/java/javamoney/ri/convert/provider/EZBExchangeRateProvider.java