Adding bignum as a explicit dependency
Merge pull request #1220 from financeCoding/bignum_dep

Adding bignum as a explicit dependency
Deleted leftover services_common.dart in lib.  Moved ServiceActionEvent from utils to services/services_common.dart (exported by services).  Added "as analyzer" to analyzer.dart and removed "as common" from services_common import to make services_common classes first-class and shadowed analyzer classes second-class.
Merge branch 'umop-services-refactor2' of https://github.com/dart-lang/spark into umop-services-refactor2
Merge pull request #1223 from dart-lang/umop-services-refactor2

Refactoring services for clarity and consolidation