Adding kernelsmith's -a datastore opt

Works well enough on its own. Note that you cannot mix -g and -a since
set doesn't actually parse out dash options in a OptParse sort of way.

That said, setg -a seems to work well. This mixing options business
will need to be addressed soon, but that day is not today.

[Closes #514]

lib/msf/ui/console/command_dispatcher/core.rb

@@ -1703,6 +1703,14 @@ class Core
 			global = true
 		end
 
+		# Decide if this is an append operation
+		append = false
+
+		if (args[0] == '-a')
+			args.shift
+			append = true
+		end
+
 		# Determine which data store we're operating on
 		if (active_module and global == false)
 			datastore = active_module.datastore
@@ -1760,9 +1768,13 @@ class Core
 			return true
 		end
 
-		datastore[name] = value
+		if append
+			datastore[name] = datastore[name] + value
+		else
+			datastore[name] = value
+		end
 
-		print_line("#{name} => #{value}")
+		print_line("#{name} => #{datastore[name]}")
 	end
 
 	#
@@ -2278,7 +2290,7 @@ class Core
 	# Returns the revision of the framework and console library
 	#
 	def cmd_version(*args)
-		svn_console_version = "$Revision: 14065 $"
+		svn_console_version = "$Revision: 15168 $"
 		svn_metasploit_version = Msf::Framework::Revision.match(/ (.+?) \$/)[1] rescue nil
 		if svn_metasploit_version
 			print_line("Framework: #{Msf::Framework::Version}.#{svn_metasploit_version}")