not going to be possible at this time unless someone seriously hacks Spartan itself locally. These types of programs work as a browser plugin and Microsoft hasn't released the extensibility set for Spartan as of yet. Flash is installed as a plugin in the current build, but there is not a way to add or remove them.
Hope an adblocker does come, can't stand these random ads popping up all over the pages. Especially with IE 11 where, its supposed to be faking as other browsers, cause of which all the ads keep taking me to play store.