Auto-detect if colors are supported

Not all output supports colors. For example, cron doesn't. This copies
the autodetection from Kafo to disable colors if needed.

lib/foreman_maintain.rb

@@ -68,6 +68,7 @@ def setup(options = {})
 
       # using a queue, we can log the messages which are generated before initializing logger
       self.config = Config.new(options)
+      configure_highline
       load_definitions
       init_logger
       update_path
@@ -102,6 +103,10 @@ def load_definitions
       end
     end
 
+    def configure_highline
+      HighLine.use_color = self.config.use_color?
+    end
+
     def cache
       ObjectCache.instance
     end

lib/foreman_maintain/config.rb

@@ -25,6 +25,11 @@ def initialize(options)
       @foreman_port = @options.fetch(:foreman_port, 443)
     end
 
+    def use_color?
+      # TODO: read config option?
+      ::ENV['TERM'] && !`which tput 2> /dev/null`.empty? && `tput colors`.to_i > 0
+    end
+
     private
 
     def load_log_configs