Add "Open wiki page" button to details on completed items.

Opens the file's wiki page in an in-app browser, with a menu item
allowing to open in external browsers.

BrowserHelper class manages the action sheet for this, can detect:
* Safari (always on)
* Chrome
* Opera Mini
* Dolphinm
Merge remote-tracking branch 'upstream/master'
Implemented failure blocks for operations
Added alerts for certain failures (ex. incorrect credentials, refresh failed, upload failed, etc.)
Only enable 'Upload' button when there are files queued for upload