null values in columns handling fixed
Merge pull request #98 from IDgis/null-in-filter

null values in columns handling fixed
indices added for foreign keys
Merge pull request #100 from IDgis/database-indices

indices added for foreign keys
last_import_job and last_service_job reimplemented
Merge pull request #101 from IDgis/last-job-views

last_import_job and last_service_job reimplemented
timeout stuff moved into AbstractStateMachine
service jobs are no longer parallel executed
InitiatorDispatcher implemented to separate handling of job types
bugfix: redundant initiator feedback removed
PgServer.DEFAULT_PORT -> PG_PORT
LoaderSessionInitiator.dataSourceBusy parameter removed
Loader: explicit tracking of busy data sources implemented
don't acknowledge job until loader session is actually started

This ensures that the requested data source is properly marked to be
busy by the loader before another job is initiated which potentially
applies the very same data source.
Merge pull request #102 from IDgis/job-exec

service job execution fixes
properly close metadata document
Merge pull request #103 from IDgis/metadata-closed

properly close metadata document
schemaName and tableName converted to lowercase
Merge pull request #104 from IDgis/lowercase-tablename

schemaName and tableName converted to lowercase
ask and askAssert moved to separate class