Fix the link to the Ubuntu installation instructions
Always call `git fetch edx` before finding PR branches
Merge pull request #4341 from edx/db/release-script-always-fetch

Always call `git fetch edx` before finding PR branches
Merge pull request #4333 from edx/ned/fix-readme-links

Fix the link to the Ubuntu installation instructions
Puts course listings in a sane order
revising markup and styling for listing header on LMS course dashboard