Added support for Java 9 and up

[MPParsley]

Support for java > 8 is broken.

The code assumes that java -version outputs 1.x:

    if ( java.version[ 0 ] !== '1' || ( java.version[ 0 ] === '1' && java.version[ 2 ] <= '8' ) ) {
      throw new Error( '\nUnsupported Java version used: ' + java.version + '. v1.8 is required!' );
    }

Java 9 java -version:

java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

Java 10 java -version:

java version "10.0.1" 2018-04-17
Java(TM) SE Runtime Environment 18.3 (build 10.0.1+10)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.1+10, mixed mode)

Fixed the check and updated the README to reflect support for Java 8+.

[jzaefferer]

I don't think grunt-html should be responsible to test the Java version. With composer it's possible to test for the php/java version perhaps a similar approach exists for npm?

Or we remove that check altogether?

All checks have failed

The linter is complaining about some silly missing spaces. Could you check that out?

[MPParsley]

Hi @jzaefferer, I fixed the linter issues. I'm new to this type of JavaScript formatting with spaces all over the place :).

[jzaefferer]

Yeah, its a special style. I stopped using it on newer projects a while ago.

Anyway, this looks fine now, I'll merge. Thanks for the contribution!