Replaced ajax calls from prototype to jquery.

- Replaced occurrences of Ajax.Request to $j.ajax
- Changed default type for ajax calls to be "POST", this was "GET" by default.
- Changed occurrences or "Parameters" on ajax calls to "data", jquery expects "data" to be present that it uses to convert to a querystring and send it upto the server.
- Changed miq_dhtmlxtoolbar.js to strip out "?" from the params that is the first character in the button.url_parms string, jquery expects data to be a key/value pair.

Issue #1150
Merge pull request #1225 from h-kataria/ajax_calls_conversion_to_jquery

Replaced ajax calls from prototype to jquery.