Refs #10450. Enable unit test to test numerical operation.

On the TimeSeriesProperty such as min, max, avarage and etc.

On branch feature/10450_record_order_by_runnumber

	modified:   ../Mantid/Framework/PythonInterface/test/python/plugins/algorithms/ExportExperimentLogTest.py
Refs #10450.  Added sorting functionality to algorithm.

And enable the algirthm to remove bad character ('\x0') automatically.
Unit test is added for the new features

On branch feature/10450_record_order_by_runnumber

      modified:   ../Mantid/Framework/PythonInterface/plugins/algorithms/ExportExperimentLog.py

      modified:   ../Mantid/Framework/PythonInterface/test/python/plugins/algorithms/ExportExperimentLogTest.py
Refs #10450.  Added a new property to algorithm.

to override the log value from workspace.  and
a new unit test is added for the new feature.

On branch feature/10450_record_order_by_runnumber

      modified:   ../Mantid/Framework/PythonInterface/plugins/algorithms/ExportExperimentLog.py
      modified:   ../Mantid/Framework/PythonInterface/test/python/plugins/algorithms/ExportExperimentLogTest.py
Refs #10450. Consider the case of duplicated records.
Refs #10450.  Added an optional feature to remove records.

Optional feature to have remove records with duplicated value in sample
log that is to be ordered by.
Refs #10450. Cleaned up the log output.
Merge branch 'feature/10450_record_order_by_runnumber'