Removes Static Analyzer Warning

The function dispatch_source_create can return NULL and clang's static analyzer complains about this.

The code is moved inside a if-branch to execute it only when deleteTimer is not NULL.
Rectify mapping to ASL log level

1. Switch on logFlag rather than logLevel. logFlag varies per log messages,
   while logLevel is constant at file or even global scope.
2. Use the LOG_FLAG_* constants for each case clause.
Fixing more dispatch_get_current_queue warnings
Touching a few Xcode projects
Merge pull request #70 from rsobik/static_analyzer_fix

Removes Static Analyzer Warning
Merge branch 'master' of github.com:robbiehanson/CocoaLumberjack
Merge pull request #78 from kastiglione/asl-log-level

Rectify mapping to ASL log level