Delete duplicate doc for Salt masterless provisionner 

there is a other doc file for this called salt.html.markdown which contain a better history
 #269 Make local_state_tree option not mandatory

Update and rename salt.html.markdown to salt-masterless.html.markdown
salt.html.markdown had a better history and formatting
And remove local_state_tree from required option from code and docs
Merge pull request #269 from rach/master

provisioner/salt-masterless: `local_state_tree` should not be mandatory