get-prebuilts: Use https for Term.apk fetch

* Use secure protocol when fetching prebuilt APKs to avoid a MITM attack
  that could send a malicious APK instead.

Change-Id: If9dfc8bdc6f5a8ac360f40fe3fb423455082d224
Merge pull request #1 from CyanogenMod/cm-11.0

get-prebuilts: Use https for Term.apk fetch