ForexTester allows you to import unlimited number of currency pairs and years of history data almost in any possible text format (ASCII *.csv, *.txt) and in MetaTrader4 history format (*.hst). We strongly recommend to import 1 minute data for accurate testing (it is possible to import higher timeframes but testing results coud be not as good).

Here you can download history data for the most common currency pairs (Source: Forexite. Ltd):

Price: Bid   Time: GMT+1 (Central European Time)   Quality: one of the best from free sources

Also we can recommend Data Bank provided by Forex broker Alpari Ltd.