use elasticsearch version 0.90.8 and move from testNG to junit

- use ElasticSearchIntegrationTest
- use ElasticsearchAssertions
- index random
fix doc values lookup

Check isEmpty() before casting to Longs or Strings. If a segment does
not conatain any document with the looked up field, the lookup will
return an instance of Empty instead of Longs/Strings that contains no
value. The search will then fail with a ClassCastException.
fix popularity test

The doc rec-0 got the same score as rec5-9 so rec0 cannot
be assumed to be at osition 5 when retrieving result.
Adding 1 to the "number" field fixes that.