Fixes harded coded Sun JVM in config and env

Addressing the issue raised in JIRA 2944, this is ensuring that
Accumulo will be correctly configured for any Java vendor.

A new question is being asked in the bootstrap_config.sh for Java vendor. This is then used to set GC settings, exclude/include JAXP implementation in ACCUMULO_OPTS. Also, default NRG provider is being injected as system property on command line since IBM JVM does not have SUN registered as default provider.
This line looks like it belongs in the other branch of the if.