NO-JIRA: JavaDoc improvements, and minor tidying up of test and logging code.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1501274 13f79535-47bb-0310-9956-ffa450edef68
PROTON-343: initial implementation of logging, including the central class ProtonLogger
and category logger implementations for java.util.logging (the default), standard out and SLF4J.
Still to do:
- Implementations in proton-jni and proton-c
- Define the full set of logging functions in EngineLogger et al.
- Modify existing Proton classes to actually use the new logging classes.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1501276 13f79535-47bb-0310-9956-ffa450edef68
PROTON-343: temporarily remove SLF4JCategoryLogger until the SLF4J dependency can be added to the CMake build

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1501318 13f79535-47bb-0310-9956-ffa450edef68