Add SDK 1.14rc1 to -dev instance for testing
Add 'permissions' to allowed keys.

SDK 1.14 will add a 'permissions' key to package.json, initially used only for allowing addons to opt-in to running in private browsing windows, with other potential uses in the future. This commit adds support for the key so developers don't get errors when trying to add the key to their addons.(cherry picked from commit 350f400829fea7990acfab865108f8fa97282290)
Merge pull request #187 from KWierso/master

Add SDK 1.14rc1 to dev instance of Builder for testing.