Changes to base Client and unit tests

- Client.java: Changed runTransaction to return matching Map object
instead of HashMap
- Utility.java: Changed readRequest to take in a filename for XML
request, modified javadoc, changed StringBuffer to StringBuilder
- Associated changes to test client classes as related to Utility.java
change and general format cleanup: ClientTest.java, ConnectionTest.java,
HttpClientConnectionTest.java, JDKHttpURLConnectionTest.java,
XmlClientTest.java