2.10.4-RC2

Removed troublesome HTML comment that messed up Jekyll.
Fix link escaping for Maven Central.
Remove leading/trailing blank lines from download page

Which seemd to confuse Jekyll.
Merge pull request #40 from retronym/release/2.10.4-RC2

2.10.4-RC2
Merge branch '2.10.x' of github.com:scala/make-release-notes

Conflicts:
	hand-written.md
	src/main/scala/MakeDownloadPage.scala
Merge pull request #42 from adriaanm/master

Merge 2.10.x into master.