js: removed Key.armor property in synchronous use

• src/Key.js The synchronous mode for a Key does not offer an armor/ armored property anymore. This frees up a lot of performance issues, also the armored expoort is expected to change quite often, so a cached version is not advisable.

• hasSecret/getHasSecret is now refactored, to reflect their uses. With get('hasSecret') there is a method that fetches the result.

• src/Key.js also some refactoring