Implemented analyser in service and updated relevant code in Spark
Renamed analyzer_common to services_common and moved to services.  Exporting services_common so that it doesn't need to be imported by users of services.dart
Review fixes (renamed File -> ServiceFile and wrote dart doc)
Merge pull request #1211 from dart-lang/umop-services-analysis_merge

Implemented analyzer in service and updated relevant code in Spark.