fixed the test of elasticsearch
Merge pull request #1138 from ChaoPang/master

fixed the test of elasticsearch
remove <property name=eclipselink.persistence-context.flush-mode value=commit/> from PersistenceGen.xml.ftl
Merge pull request #1140 from ChaoPang/master

remove <property name="eclipselink.persistence-context.flush-mode" value="commit"/> from PersistenceGen.xml.ftl
put back <property name=eclipselink.persistence-context.flush-mode value=commit/>
Merge pull request #1141 from ChaoPang/master

put back <property name="eclipselink.persistence-context.flush-mode" value="commit"/>
Simplified DataService.
Removed EntitySource, EntitySourceFactory.
Just use DataService.addRepository(repository) to register a repository to be used ad data backend
Merge branch 'master' of https://github.com/molgenis/molgenis
Remove test
Merge pull request #1142 from erwinwinder/master

Simplified DataService
Added CsvRepositorySource
Added test
Added test
Updated javadoc
Updated documentation
Merge pull request #1143 from erwinwinder/master

Added CsvRepositorySource, Updated documentation
add nullcheck - input files without a dataset gave a nullpointer error.