fix(seed checker): don't fail if the user provides more seed words than required

Previously, if the user pushed the back button after supplying a seed word,
then returned and entered the required three, the seed check would fail due to
there being more words supplied than required.

app/reducers/onboarding.js

@@ -348,7 +348,7 @@ onboardingSelectors.reEnterSeedChecker = createSelector(
   seedIndexesArrSelector,
   reEnterSeedInputSelector,
   (seed, seedIndexArr, reEnterSeedInput) =>
-    seedIndexArr.length === Object.keys(reEnterSeedInput).length &&
+    Object.keys(reEnterSeedInput).length >= seedIndexArr.length &&
     seedIndexArr.every(
       index => reEnterSeedInput[index] && reEnterSeedInput[index] === seed[index - 1]
     )