Logger.getLevel() returns OFF if this.level isn't set.

This is useful especially if blammo isn't configured, ie. if the project doesn't contain a configuration file. In this case, we assume that no log should be done.
Logger.traceEntry() and Logger.traceExit() don't do anything if Logger.level < TRACE

This commit makes both functions' behavior consistent with Logger.log().
Fix 40b19a557573a5f6faa80395b6e4b8ea2569b4f3
Logging level checks for Logger.traceEntry() and Logger.traceExit() are now done at runtime

This allows to dynamically enable or disable the methode tracing by calling Logger.setLevel().
Revert 19fb1e3d44363a8d25c7ebab8faa051d1ae26767, f8d592897234b0d2a735eca04b20ccbe44f694e2, 40b19a557573a5f6faa80395b6e4b8ea2569b4f3
Merge pull request #3 from PaulMougel/master

Really disable blammo if no configuration is specified