Update readme and the config sample to add the cache setting

README.md

@@ -17,6 +17,7 @@ The JSON configuration file should look like the following.
     {
         "url":"str",
         "name":"str",
+        "cache": 10,
         "encoding":"str",
         "filters":{
             "name":{
@@ -60,6 +61,7 @@ The JSON configuration file should look like the following.
 Only the `url` and the `name` field are mandatory.  
 - `url`: specify the url to find the calendar  
 - `name`: name to identify the calendar
+- `cache`: if present cache the remote calendar according to the interval set in minutes
 - `encoding`: specify the encoding to use  
   
 
@@ -87,4 +89,4 @@ If multiple calendars are specified in the configuration list, their events will
 Once the config file is created, the corresponding HTTP endpoint is accessible.  For example, if the file `app/config/my-calendar.json` contains the configuration, the HTTP endpoint will be `http://localhost:8088/my-calendar`.
 
 ## Limitations
-Currently, the application only merges events of the ics feeds, the alarms and todos are not supported.  There is no mechanism to handle the case where an incoming feed becomes unavailable.
+Currently, the application only merges events of the ics feeds, the alarms and todos are not supported.  

config-sample.txt

@@ -1,6 +1,7 @@
 [
     {"url": "str",
      "name": "str",
+     "cache": 10,
      "encoding": "str",
      "filters": {
          "name": {"exclude": "RegEx", "includeOnly": "RegEx", "ignoreCase": true},