Show a message if pgp is not present

* Try to locate gpg.exe in the bootstrapper and show an appropriate dialog
  to the user if it isn't found.
Ensure all messages have version tag

Add version tag to hellos

Update obelisk to unsystem rather than airbitz
Migrate to coinkite obelisk

Revert unnecessary v key
Merge pull request #935 from hoffmabc/feature-add-version-to-send

Feature add version to send
Merge pull request #946 from yagoulas/win_pgp_check

Show a message if pgp is not present on windows