Merge #136: Change the nix-bitcoin deployment from forking this repo to importing the module

b2e15c17b8 docs: Update to new deployment method (import instead of fork) (Jonas Nick)
5ed0284db9 Add fetch-release script (Jonas Nick)
c303cd47e4 Add push-release.sh helper (Jonas Nick)
705d187a35 examples/shell.nix: don't run shellHook on subsequent nix-shells (Erik Arvstedt)
65039be656 docs: Remove duplicate instructions (Jonas Nick)
455c5664c9 docs: Replace tabs with spaces (Jonas Nick)
8aa4714979 docs: Update NixOS version (Jonas Nick)
9df22a2764 add deploy-qemu-vm.sh example (Erik Arvstedt)
548ced1994 README: Add Example section (Jonas Nick)
44ccbb91d0 Clean up development shell.nix (Jonas Nick)
abcee651d3 add deploy-container.sh (Erik Arvstedt)
5dadea310c add deploy-nixops.sh (Erik Arvstedt)
0c74c365de mention performance loss with hardened kernel profile (Erik Arvstedt)
f3121892ef move main module import to configuration.nix (Erik Arvstedt)
0c0978c007 extract module 'deployment/nixops.nix', add option 'deployment.secretsDir' (Erik Arvstedt)
87d0286498 Change the nix-bitcoin deployment from forking this repo to importing the module (Jonas Nick)

Pull request description:

Top commit has no ACKs.

Tree-SHA512: 18e8b71f42715c5e82e2dafde9dcc965594d76aacc6be7ee2ec746a9510065749cc65331687a57d7140f45779c3b7867f6260ec224d361fb5a477062a27d6e4c

pkgs/nixops/release.nix.patch

@@ -43,3 +43,14 @@
                                     ('destDir',     'string'),
                                     ('user',        'string'),
                                     ('group',       'string'),
+
+--- a/nixops/ssh_util.py
++++ b/nixops/ssh_util.py
+@@ -278,6 +278,7 @@ class SSH(object):
+
+         'timeout' specifies the SSH connection timeout.
+         """
++        flags = shlex.split(os.getenv('NIXOPS_SSH_OPTS', '')) + flags
+         master = self.get_master(flags, timeout, user)
+         flags = flags + self._get_flags()
+         if logged: