Description of problem:
Default timeout for 'Scan for updates' is 30s but this operation usually takes longer. After 30s following warning is displayed:

Failed to scan for updated plugins. A request timeout has expired after 30000 ms. This occurred because the server is taking a long time to complete this request. Please be aware that the server may still be processing your request and it may complete shortly. You can check the server logs to see if any abnormal errors occurred.

so a user has to check server log to find out if the operation was successful.


Version-Release number of selected component (if applicable):
Version: 3.1.1.ER2
Build Number: f546515:4eb3f2c

How reproducible:
Always

Steps to Reproduce:
1. clean installation of JON prepared and running 
2. cp jon-plugin-pack-eap-3.1.1.ER2/* jon-server-3.1.1.ER2/plugins/
3. Administration->Agent plugins->Scan for Updates
  
Actual results:
Failed to scan for updated plugins. A request timeout has expired after 30000 ms. This occurred because the server is taking a long time to complete this request. Please be aware that the server may still be processing your request and it may complete shortly. You can check the server logs to see if any abnormal errors occurred.

Expected results:
A user is informed about final operation result.

Additional info:
related to bug 828296