Various EAS related changes related to accounts and services.

* Renamed ISyncManager/ISyncManagerCallback to IEmailService/IEmailServiceCallback
* Restored ExchangeTransportExample to its original state; created ExchangeStore to
  handle validation functionality instead; updated stores.xml to reflect these changes.
* Add support for AccountManager in EAS code (this is necessary for the contacts and
  calendar providers to work with syncable data); created EasAuthenticatorService to
  as our authenticator, which required adding authenticator.xml and modifying the
  manifest to register our service with AccountManager metadata
* Created EmailServiceProxy as a convenience for the UI in calling into the EAS
  service; created EmailServiceStatus class for status codes in callbacks.
11 files changed