dvc: add -v|--verbose and -q|-quiet

These are cmdline shortcuts to change dvc's verbosity
without fiddling around with loglevel in dvc.conf.
Both are added and handled as a common options for
all dvc commands in base cmd class.

dvc/command/base.py

@@ -41,10 +41,13 @@ class CmdBase(object):
         self._settings = settings
 
         parser = argparse.ArgumentParser()
+        self.define_common_args(parser)
         self.define_args(parser)
 
         self._parsed_args, self._command_args = parser.parse_known_args(args=self.args)
 
+        self.process_common_args()
+
     @property
     def settings(self):
         return self._settings
@@ -88,6 +91,16 @@ class CmdBase(object):
                             help='Lock data item - disable reproduction. ' +
                                  'It can be enabled by `dvc lock` command or by forcing reproduction.')
 
+    def define_common_args(self, parser):
+        parser.add_argument('--quiet', '-q', action='store_true', default=False, help='Be quiet.')
+        parser.add_argument('--verbose', '-v', action='store_true', default=False, help='Be verbose.')
+
+    def process_common_args(self):
+        if self._parsed_args.quiet and not self._parsed_args.verbose:
+            Logger.be_quiet()
+        elif not self._parsed_args.quiet and self._parsed_args.verbose:
+            Logger.be_verbose()
+
     @property
     def no_git_actions(self):
         return self.parsed_args.no_git_actions

dvc/logger.py

@@ -18,6 +18,14 @@ class Logger(object):
     def set_level(level):
         Logger._logger.setLevel(Logger.LEVEL_MAP.get(level.lower(), 'debug'))
 
+    @staticmethod
+    def be_quiet():
+        Logger._logger.setLevel(logging.CRITICAL)
+
+    @staticmethod
+    def be_verbose():
+        Logger._logger.setLevel(logging.DEBUG)
+
     @staticmethod
     def error(msg):
         return Logger._logger.error(msg)