Logstash 2.0 should require Java 8

[jordansissel]

Oracle marked the EOL of Java 7 in April 2015, and as of July 2015 they no longer provide downloads for Java 7.

Logstash 2.0 is a good time to upgrade to Java 8. Benefits being:

• This version of Java still receives improvements
• concurrent-ruby (a dependency library) will require Java 8 for v1.0
• We can explore using JSR-310, the new Java 8 Date/Time tooling as a replacement to Joda-Time. Benefit that it's native and supports nanosecond-precise times (Joda is millisecond-precise).

[runningman84]

That should not be a big deal because elasticsearch requires java 8 too.

[jasontedor]

That should not be a big deal because elasticsearch requires java 8 too.

@runningman84 That's not true for the 2.x line of Elasticsearch (the current line), but is true for the next major release of Elasticsearch.