support text log level updates

Change-Id: Iac1ea7952ca0f56f0289070cca17f652c6cd4045
updated R package

Change-Id: I5e6e82a8d69fee1ad83f5455ce3cfbe69f3f05dd
testcase update with string log level and corresponding updates to the logger class

Change-Id: I44ed44438eb32739394e266d84207d59732a2c20