modified dispatcher flush()

Applied a correction for flush() to work correctly with bulk upload, now
deletes "number of records sent" rather than just the last record
regardless of number sent.
Also changed code so that the default "maxItemsPerPost" is 1 (ie single
record posting) adding a value will effectively bring bulk upload into
play (max still 250)
Merge pull request #43 from otherWIP/development

modified dispatcher flush()