make RiverMouth.flush() also work if no time based blukflush is enabled, RiverMout.startup() now threadsafe, minor cleanups
fixed random fail of org.xbib.elasticsearch.river.jdbc.strategy.ingest.RiverJobTests SearchPhaseExecutionException (Ingest RiverJobTest Line 54)
again 'fixed' problems with random failing testcases - now the hard way (error occurs even before jdbcriver gets instantiated so i guess thats not related to code changes hopefully)
Merge pull request #225 from salyh/bulkfixes

RiverMouth.flush() suggest alternative,  RiverMouth.startup() refactored, and minor code cleanups