* Generate a new runid for each start of godis
* Add info command
* Add info command
* Generate a new runid for each start of godis
* Add unittests for the info command
* Add info command
* Record the number of clients in the current Godis server
* Add info command
Add "copy" command,also fixes the out of range error of select when the number is negative.
Move execCopy to "keys.go" ,
Add test in "keys_test.go",
Add "copy.go" and "copy_test.go" file.