add alternative sftp settings file (#3006)

* add alternative sftp settings file

* update for possible multiple alt* numbered files

Global/SublimeText.gitignore

@@ -12,6 +12,7 @@
 
 # SFTP configuration file
 sftp-config.json
+sftp-config-alt*.json
 
 # Package control specific files
 Package Control.last-run