Add XAttrs Sync Gateway Config File to the tutorial repo

[Deleted user]

Add a new Sync Gateway Config to the tutorial repo to include the following

• Enable extended attribute support
  "to-do": {
  "import_docs": "continuous",
  "unsupported": {
  "enable_extended_attributes": true
  },

• Add version compatibility note in the config file - Need Couchbase Server 5.0 or newer and Sync Gateway 1.5 or newer

[sethrosetter]

Can't comment in json. The readme should be updated.

[sethrosetter]

closed via - #128