rest: add backup parameter

Support parsing of "backup" parameter inside incoming requests.

Prepare ogClient support for backup image creation in "image create"
operation.

src/restRequest.py

@@ -36,6 +36,7 @@ class restRequest:
 		self.echo = None
 		self.code = None
 		self.seq = None
+		self.backup = None
 
 	def parser(self,data):
 		self.request_line, self.headers_alone = data.split('\n', 1)
@@ -107,6 +108,9 @@ class restRequest:
 			if "code" in json_param:
 				self.code = json_param["code"]
 
+			if "backup" in json_param:
+				self.backup = json_param["backup"]
+
 	def get_method(self):
 		return self.method
 
@@ -151,3 +155,6 @@ class restRequest:
 
 	def getCode(self):
 		return self.code
+
+	def getBackup(self):
+		return self.backup