"JavaFX runtime not found": Use a 1.9-style named regexp to correctly parse ENV_JAVA["java.runtime.version"]

A few of the matches could be dropped, but leaving them in future-proofs the regexp.

See: http://rubular.com/r/UyWaY5qjIk

Parses:
1.8.0_10
1.8.0_10-u2-b23
1.8.0-ea-b75
1.7.0_10-ea-b07
1.8.0-ea-b63
1.6.0_33
1.6.0_31-b05
1.6.0_17-b04
1.7.0-u2-b21
1.7.0_13-b20
Merge branch 'master' of github.com:jruby/jrubyfx