gpg: allow GPG 2.1.11+ (to support Ubuntu 16.04 & Mint 18)

README-GPG.md

@@ -4,7 +4,7 @@ Thanks!
 
 # Installation
 
-First, verify that you have GPG 2.1+ installed
+First, verify that you have GPG 2.1.11+ installed
 ([Debian](https://gist.github.com/vt0r/a2f8c0bcb1400131ff51),
 [macOS](https://sourceforge.net/p/gpgosx/docu/Download/)):
 
@@ -13,6 +13,9 @@ $ gpg2 --version | head -n1
 gpg (GnuPG) 2.1.15
 ```
 
+This GPG version is included in [Ubuntu 16.04](https://launchpad.net/ubuntu/+source/gnupg2)
+and [Linux Mint 18](https://community.linuxmint.com/software/view/gnupg2).
+
 Update you TREZOR firmware to the latest version (at least v1.4.0).
 
 Install latest `trezor-agent` package from GitHub:

trezor_agent/gpg/__main__.py

@@ -80,7 +80,7 @@ def main_create():
                 'change without backwards compatibility!')
 
     existing_gpg = keyring.gpg_version().decode('ascii')
-    required_gpg = '>=2.1.15'
+    required_gpg = '>=2.1.11'
     if semver.match(existing_gpg, required_gpg):
         run_create(args)
     else: