CASC-200 Introduce Properties File Configuration Option

Problem: We can configure via JNDI, WebXML (or both) but not by properties file.
Solution: Introduce a method to use property files.
Yes:
https://github.com/Jasig/java-cas-client/blob/master/cas-client-core/src/main/java/org/jasig/cas/client/configuration/BaseConfigurationStrategy.java#L69