Remove app from 'Recently Used Apps' list.

Add the setting to the app main activity in the manifest file.
Merge pull request #54 from AlexKolpa/recent-apps-list-hiding

Remove app from 'Recently Used Apps' list.
Merge branch 'master' into encrypt-files
Added callback structure to en/decryption

Using IOnResult<T> from @OlivierHokke, I've completed the concurrent approach of encrypting.