Moved compareQueries() and runQuery() to the base class EnsTestCase
getSpeciesDatabaseMap()is not used in MultiDatabaseTestCase any more
usage() is not needed
Move away from getSpeciesDatabaseMap()

The base class AbstractSingleDBTestCaseWithCoreDBs contains a new method
getSpeciesCoreDbMap() to get a mapping between each species and its core database
Removed getSpeciesDatabaseMap() (it is unused)
Merge pull request #15 from muffato/refactor_MultiDatabaseTestCase

Refactor MultiDatabaseTestCase