Implementing the Session:all_dbs method

This method makes an http request to the _all_dbs http uri of the
couchdb uri and decodes the returned json value. This commit makes
lua-couchdb depend on lua-json and lua-socket2.

Another small change was that now we return the _M var in the end of
the module. And now, Session object is not local anymor, that was
causing an error!

couchdb.lua

@@ -14,8 +14,11 @@
 -- along with this program. If not, see <http:https://www.gnu.org/licenses/>
 
 module("couchdb", package.seeall)
+local json = require("json")
+local socket = require("socket")
+local http = require("socket.http")
 
-local Session = {uri="http:https://localhost:5984"}
+Session = {uri="http:https://localhost:5984"}
 
 function Session:new(uri)
  local o = {}
@@ -27,6 +30,18 @@ function Session:new(uri)
  return o
 end
 
+function Session:all_dbs()
+ local url = self.uri .. "/_all_dbs"
+ local body, code, headers, human_readable_error = http.request(url)
+ if code ~= 200 then
+ error({message=human_readable_error})
+ else
+ return json.decode(body)
+ end
+end
+
 function Session:create_database(name)
  -- FIXME: Build a json request and then send it through HTTP
 end
+
+return _M