Transition from TravisCI to GitHub CI (#7444)

Convert the continuous integration process to use GitHub's internal
CI cloud.  Allows us to run up to 20 jobs in parallel, speeding up
CI immensely.  Keep a short Travis-CI run, too, just for sanity and backup.

Uses new keys and secret when publishing a release to
esp8266.github.io.

package/upload_release.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+
+from github import Github
+import argparse
+import collections
+import glob
+import json
+import mimetypes
+import os
+
+parser = argparse.ArgumentParser(description='Upload a set of files to a new draft release')
+parser.add_argument('--user', help="Github username", type=str, required=True)
+parser.add_argument('--token', help="Github Personal Access Token (PAT)", type=str, required=True)
+parser.add_argument('--repo', help="Repository", type=str, required=True)
+parser.add_argument('--tag', help="Release tag", type=str, required=True)
+parser.add_argument('--name', help="Release name", type=str, required=True)
+parser.add_argument('--msg', help="Release message", type=str, required=True)
+parser.add_argument('files', nargs=argparse.REMAINDER)
+args = parser.parse_args()
+
+if len(args.files) == 0:
+    print("ERROR:  No files specified")
+    quit()
+
+gh = Github(login_or_token=args.token)
+repo = gh.get_repo(str(args.repo))
+release = repo.create_git_release(args.tag, args.name, args.msg, draft=True)
+for fn in args.files:
+    print("Uploading file: " + fn)
+    release.upload_asset(fn)