I need to tune below option "Allows contributors to add or edit scriptable Web Parts" for particular web-application .
For a bit of context, the page you are in can be found in
Central Administration > Security > Manage web part security
There are 3 properties there, all can be accessed through server object model.
$wa = get-spwebapplication http://contoso $wa.AllowPartToPartCommunication $wa.AllowAccessToWebPartCatalog $wa.AllowContributorsToEditScriptableParts
You can tweak as a regular bool
$wa.AllowContributorsToEditScriptableParts = $true $wa.Update()
If you are looking for solutions in the context of Office 365, I can't help you, but perhaps this can point you in the right direction.