Backport release automation scripts for v0.30.3

* Release management using CircleCI (#3498)

* Release management using CircleCI

* Changelog updated

* Fix for wrong version tag (#3517)

* Fix for wrong version tag (tag on the release branch instead of master)

* Release message changelog link fix (#3519)

scripts/release_management/github-draft.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+
+# Create a draft release on GitHub. By default in the tendermint/tendermint repo.
+# Optimized for CircleCI
+
+import argparse
+import httplib
+import json
+import os
+from base64 import b64encode
+
+def request(org, repo, data):
+  user_and_pass = b64encode(b"{0}:{1}".format(os.environ['GITHUB_USERNAME'], os.environ['GITHUB_TOKEN'])).decode("ascii")
+  headers = {
+    'User-Agent': 'tenderbot',
+    'Accept': 'application/vnd.github.v3+json',
+    'Authorization': 'Basic %s' % user_and_pass
+  }
+  
+  conn = httplib.HTTPSConnection('api.github.com', timeout=5)
+  conn.request('POST', '/repos/{0}/{1}/releases'.format(org,repo), data, headers)
+  response = conn.getresponse()
+  if response.status < 200 or response.status > 299:
+    print("{0}: {1}".format(response.status, response.reason))
+    conn.close()
+    raise IOError(response.reason)
+  responsedata = response.read()
+  conn.close()
+  return json.loads(responsedata)
+
+
+def create_draft(org,repo,branch,version):
+  draft = {
+    'tag_name': version,
+    'target_commitish': '{0}'.format(branch),
+    'name': '{0} (WARNING: ALPHA SOFTWARE)'.format(version),
+    'body': '<a href=https://github.com/{0}/{1}/blob/{2}/CHANGELOG.md#{3}>https://github.com/{0}/{1}/blob/{2}/CHANGELOG.md#{3}</a>'.format(org,repo,branch,version.replace('.','')),
+    'draft': True,
+    'prerelease': False
+  }
+  data=json.dumps(draft)
+  return request(org, repo, data)
+
+if __name__ == "__main__":
+  parser = argparse.ArgumentParser()
+  parser.add_argument("--org", default="tendermint", help="GitHub organization")
+  parser.add_argument("--repo", default="tendermint", help="GitHub repository")
+  parser.add_argument("--branch", default=os.environ.get('CIRCLE_BRANCH'), help="Branch to build from, e.g.: v1.0")
+  parser.add_argument("--version", default=os.environ.get('CIRCLE_TAG'), help="Version number for binary, e.g.: v1.0.0")
+  args = parser.parse_args()
+
+  if not os.environ.has_key('GITHUB_USERNAME'):
+    raise parser.error('environment variable GITHUB_USERNAME is required')
+
+  if not os.environ.has_key('GITHUB_TOKEN'):
+    raise parser.error('environment variable GITHUB_TOKEN is required')
+
+  release = create_draft(args.org,args.repo,args.branch,args.version)
+
+  print(release["id"])
+