Add suite name to the testtool log file name

Add suite name to the testtool log file name

To prevent suites using the test tool overwriting the log
file of the test tool(s) they use, add the name of the
suite to the name of the log file produced by the test
tool. This currently affects suites using the "testtool"
tool (CRUD and scaling suites). The core code in this change
was packaged into the keyword Utils.Get_Log_File_Name because
the functionality is going to be needed in the RestPerfClient
suite as well.

Change-Id: Idf5fbed8baf4b150d66e91c95c2bcaa6dbeab90b
Signed-off-by: Jozef Behran <jbehran@cisco.com>