Add meaningful library version check to .install file

Parallel to #1402846: Compatibility with VideoJS v. 3, since there is now a 3.x of VideoJS (and there aren't clear indications in the README about outside library API compatibility) I think we should add a meaningful check on videojs_get_version() in the .install, beyond just seeing if the library is installed. (This would also be a documentation task...)

This is in addition to #1403538: Add support for Libraries API since this could piggyback on Libraries API.