Add beta to the course4 box at studio.code.org.
Also properly loc the 'beta' string, and add some space for extra line of text for some locs.
Tested with extra long strings for header; they will ellipsis correctly for both beta & non-beta courses.
Center the beta text in its little grey box.
Centralise course beta? check, even for code that doesn't have a Script object.
Merge pull request #852 from code-dot-org/tallboxbeta

Add beta to the course4 box at studio.code.org.