Adding support for base64 encoded keystores and truststores

[rahulnirgude]

This change adds 2 optional configuration properties that can be set to true when the keystore location string is actually a base64 encoded keystore string Added these properties with default of false. If properties are explicitly set to true, the keystore location will be treated as a file path to the keystore (as it did before). This makes the change backwards compatible to the existing functionality. Example from the durable_consumer_with_keystore_string.properties ssl.truststore.location.as.string=true ssl.keystore.type=JKS ssl.truststore.location= ssl.keystore.location.as.string=true ssl.truststore.type=JKS ssl.keystore.location= All unit tests are passing and I added a new test to verify that the base64 encoded string works with the code changes. No changes were made to any other unit tests.