Add pageCapture permission

[ctownshend]

Expected Behavior

Currently the extension will allow you specify permissions to add to the manifest. The list of permissions does not include pageCapture. here is a complete list of available permissions. Please look to add the missing ones. https://developer.chrome.com/extensions/permission_warnings

Current Behavior

Currently the permissions that are available do not include pageCapture.

Steps to Reproduce (for bugs)

1. run the the yeoman wizard
2. notice that the permissions step includes various permissions
3. permissions does not include pageCapture

Context

Minor issue as you can add the permissions afterwards. More for completeness.

Your Environment

Mac, but not relevant