Adds support for Doctor Dump

Allows you to upload bug reports to Doctor Dump crash reporting service

The type of NBug.Core.Reporting.Info.GeneralInfo.DateTime was changed from string to DateTime because it was serialized as string with user locale
But later it will be needed as DateTime field, not just string and user locale hampers conversion to DateTime type.
Also date in user locale may be not readable by developer but DateTime type is serializied in human readable xml:dateTime format.