second round of code reviews

Changes:
- writing all counter key/value pair accumulated in a flush
  period in a single record
- changed default write to log table methods to be writeLog.
  Mirroring the original methods write and marking them as
  @Deprecated
- changed the way the flush (logger) and upload (service)
  worker interval are set to allow independent settings
-- logger/AbstractTdLogger
   added setFlushWorkerInterval API. This API is best
   used between instantiating the logger and running
   the underlying worker for it to take immediate effect.
   If not, the worker interval will still observe an additional
   round with the old interval before switching
-- service/TdLoggerService
   added a static method to modify the interval before
   the logger is instantiated.
-- service/TdLoggerService
   added also a method to DefaultTdLogger to sent a message
   (Intent) to the service to change the interval. This
   method is intended to be used to make runtime modification
   and it will cause the upload worker to observe one additinal
   round with the old interval before switching
-- consequently made the RepeatingWorker interval setting non
   static as originally implemented.

- handling HTTP request 409 as an error. Removed special case
  for creating databases.
- fixed all unit tests