Improve "make test-*", add verbose and test_files

 - Change default verbosity of tests to "not verbose"

 - Look for "test_verbose=" variable from command line to run tests in verbose mode.

   If the "test_verbose=" argument is set to anything, --verbose is added to the "perl Build test"
   command line.

   Example: make test-master test_verbose=1

 - Look for "test_files=" variable from command line to select test files to run.

   If the "test_files=" argument is set to a space separated list of files,
   test_files="<list of files>" is added to the "perl Build test" command line.

   Example: make test-node test_files="t/munin_node_proxyspooler.t t/munin_node_spoolreader.t"
Add new class Munin::Common::Logger
Replace Log4perl with Munin::Common::Logger
Replace logging in Munin::Common::TLS* with Munin::Common::Logger
Replace Munin::Master::Logger with Munin::Common::Logger
Replace Munin::Node::Logger with Munin::Common::Logger
Clean up tests
Update Build.PL and documentation
Munin::Common::Logger: Update documentation
Log errors to "screen", and debug to "syslog"
Merge branch 'feature/log-dispatch-2014' into devel